1 | /* |
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2 | * Copyright (c) 1990 The Regents of the University of California. |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms are permitted |
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6 | * provided that the above copyright notice and this paragraph are |
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7 | * duplicated in all such forms and that any documentation, |
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8 | * advertising materials, and other materials related to such |
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9 | * distribution and use acknowledge that the software was developed |
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10 | * by the University of California, Berkeley. The name of the |
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11 | * University may not be used to endorse or promote products derived |
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12 | * from this software without specific prior written permission. |
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13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
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14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
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15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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16 | */ |
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17 | |
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18 | /* |
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19 | FUNCTION |
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20 | <<sscanf>>, <<fscanf>>, <<scanf>>---scan and format input |
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21 | |
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22 | INDEX |
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23 | scanf |
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24 | INDEX |
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25 | _scanf_r |
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26 | INDEX |
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27 | fscanf |
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28 | INDEX |
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29 | _fscanf_r |
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30 | INDEX |
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31 | sscanf |
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32 | INDEX |
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33 | _sscanf_r |
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34 | |
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35 | SYNOPSIS |
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36 | #include <stdio.h> |
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37 | |
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38 | int scanf(const char *restrict <[format]>, ...); |
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39 | int fscanf(FILE *restrict <[fd]>, const char *restrict <[format]>, ...); |
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40 | int sscanf(const char *restrict <[str]>, const char *restrict <[format]>, ...); |
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41 | |
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42 | int _scanf_r(struct _reent *<[ptr]>, const char *restrict <[format]>, ...); |
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43 | int _fscanf_r(struct _reent *<[ptr]>, FILE *restrict <[fd]>, |
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44 | const char *restrict <[format]>, ...); |
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45 | int _sscanf_r(struct _reent *<[ptr]>, const char *restrict <[str]>, |
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46 | const char *restrict <[format]>, ...); |
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47 | |
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48 | DESCRIPTION |
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49 | <<scanf>> scans a series of input fields from standard input, |
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50 | one character at a time. Each field is interpreted according to |
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51 | a format specifier passed to <<scanf>> in the format string at |
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52 | <<*<[format]>>>. <<scanf>> stores the interpreted input from |
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53 | each field at the address passed to it as the corresponding argument |
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54 | following <[format]>. You must supply the same number of |
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55 | format specifiers and address arguments as there are input fields. |
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56 | |
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57 | There must be sufficient address arguments for the given format |
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58 | specifiers; if not the results are unpredictable and likely |
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59 | disasterous. Excess address arguments are merely ignored. |
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60 | |
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61 | <<scanf>> often produces unexpected results if the input diverges from |
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62 | an expected pattern. Since the combination of <<gets>> or <<fgets>> |
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63 | followed by <<sscanf>> is safe and easy, that is the preferred way |
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64 | to be certain that a program is synchronized with input at the end |
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65 | of a line. |
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66 | |
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67 | <<fscanf>> and <<sscanf>> are identical to <<scanf>>, other than the |
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68 | source of input: <<fscanf>> reads from a file, and <<sscanf>> |
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69 | from a string. |
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70 | |
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71 | The routines <<_scanf_r>>, <<_fscanf_r>>, and <<_sscanf_r>> are reentrant |
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72 | versions of <<scanf>>, <<fscanf>>, and <<sscanf>> that take an additional |
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73 | first argument pointing to a reentrancy structure. |
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74 | |
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75 | The string at <<*<[format]>>> is a character sequence composed |
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76 | of zero or more directives. Directives are composed of |
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77 | one or more whitespace characters, non-whitespace characters, |
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78 | and format specifications. |
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79 | |
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80 | Whitespace characters are blank (<< >>), tab (<<\t>>), or |
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81 | newline (<<\n>>). |
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82 | When <<scanf>> encounters a whitespace character in the format string |
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83 | it will read (but not store) all consecutive whitespace characters |
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84 | up to the next non-whitespace character in the input. |
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85 | |
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86 | Non-whitespace characters are all other ASCII characters except the |
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87 | percent sign (<<%>>). When <<scanf>> encounters a non-whitespace |
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88 | character in the format string it will read, but not store |
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89 | a matching non-whitespace character. |
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90 | |
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91 | Format specifications tell <<scanf>> to read and convert characters |
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92 | from the input field into specific types of values, and store then |
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93 | in the locations specified by the address arguments. |
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94 | |
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95 | Trailing whitespace is left unread unless explicitly |
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96 | matched in the format string. |
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97 | |
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98 | The format specifiers must begin with a percent sign (<<%>>) |
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99 | and have the following form: |
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100 | |
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101 | . %[*][<[width]>][<[size]>]<[type]> |
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102 | |
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103 | Each format specification begins with the percent character (<<%>>). |
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104 | The other fields are: |
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105 | O+ |
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106 | o * |
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107 | |
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108 | an optional marker; if present, it suppresses interpretation and |
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109 | assignment of this input field. |
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110 | |
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111 | o <[width]> |
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112 | |
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113 | an optional maximum field width: a decimal integer, |
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114 | which controls the maximum number of characters that |
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115 | will be read before converting the current input field. If the |
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116 | input field has fewer than <[width]> characters, <<scanf>> |
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117 | reads all the characters in the field, and then |
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118 | proceeds with the next field and its format specification. |
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119 | |
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120 | If a whitespace or a non-convertable character occurs |
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121 | before <[width]> character are read, the characters up |
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122 | to that character are read, converted, and stored. |
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123 | Then <<scanf>> proceeds to the next format specification. |
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124 | |
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125 | o <[size]> |
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126 | |
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127 | <<h>>, <<j>>, <<l>>, <<L>>, <<t>>, and <<z>> are optional size |
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128 | characters which override the default way that <<scanf>> |
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129 | interprets the data type of the corresponding argument. |
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130 | |
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131 | @multitable @columnfractions 0.18 0.30 0.52 |
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132 | @headitem |
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133 | Modifier |
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134 | @tab |
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135 | Type(s) |
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136 | @tab |
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137 | @item |
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138 | hh |
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139 | @tab |
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140 | d, i, o, u, x, n |
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141 | @tab |
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142 | convert input to char, store in char object |
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143 | @item |
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144 | h |
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145 | @tab |
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146 | d, i, o, u, x, n |
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147 | @tab |
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148 | convert input to short, store in short object |
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149 | @item |
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150 | h |
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151 | @tab |
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152 | D, I, O, U, X, e, f, c, s, p |
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153 | @tab |
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154 | no effect |
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155 | @item |
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156 | j |
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157 | @tab |
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158 | d, i, o, u, x, n |
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159 | @tab |
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160 | convert input to intmax_t, store in intmax_t object |
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161 | @item |
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162 | j |
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163 | @tab |
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164 | all others |
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165 | @tab |
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166 | no effect |
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167 | @item |
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168 | l |
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169 | @tab |
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170 | d, i, o, u, x, n |
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171 | @tab |
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172 | convert input to long, store in long object |
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173 | @item |
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174 | l |
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175 | @tab |
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176 | e, f, g |
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177 | @tab |
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178 | convert input to double, store in a double object |
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179 | @item |
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180 | l |
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181 | @tab |
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182 | D, I, O, U, X, c, s, p |
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183 | @tab |
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184 | no effect |
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185 | @item |
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186 | ll |
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187 | @tab |
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188 | d, i, o, u, x, n |
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189 | @tab |
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190 | convert to long long, store in long long object |
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191 | @item |
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192 | L |
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193 | @tab |
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194 | d, i, o, u, x, n |
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195 | @tab |
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196 | convert to long long, store in long long object |
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197 | @item |
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198 | L |
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199 | @tab |
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200 | e, f, g, E, G |
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201 | @tab |
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202 | convert to long double, store in long double object |
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203 | @item |
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204 | L |
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205 | @tab |
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206 | all others |
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207 | @tab |
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208 | no effect |
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209 | @item |
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210 | t |
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211 | @tab |
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212 | d, i, o, u, x, n |
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213 | @tab |
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214 | convert input to ptrdiff_t, store in ptrdiff_t object |
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215 | @item |
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216 | t |
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217 | @tab |
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218 | all others |
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219 | @tab |
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220 | no effect |
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221 | @item |
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222 | z |
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223 | @tab |
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224 | d, i, o, u, x, n |
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225 | @tab |
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226 | convert input to size_t, store in size_t object |
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227 | @item |
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228 | z |
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229 | @tab |
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230 | all others |
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231 | @tab |
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232 | no effect |
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233 | @end multitable |
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234 | |
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235 | o <[type]> |
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236 | |
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237 | A character to specify what kind of conversion |
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238 | <<scanf>> performs. Here is a table of the conversion |
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239 | characters: |
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240 | |
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241 | o+ |
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242 | o % |
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243 | No conversion is done; the percent character (<<%>>) is stored. |
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244 | |
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245 | o c |
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246 | Scans one character. Corresponding <[arg]>: <<(char *arg)>>. |
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247 | |
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248 | o s |
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249 | Reads a character string into the array supplied. |
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250 | Corresponding <[arg]>: <<(char arg[])>>. |
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251 | |
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252 | o [<[pattern]>] |
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253 | Reads a non-empty character string into memory |
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254 | starting at <[arg]>. This area must be large |
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255 | enough to accept the sequence and a |
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256 | terminating null character which will be added |
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257 | automatically. (<[pattern]> is discussed in the paragraph following |
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258 | this table). Corresponding <[arg]>: <<(char *arg)>>. |
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259 | |
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260 | o d |
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261 | Reads a decimal integer into the corresponding <[arg]>: <<(int *arg)>>. |
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262 | |
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263 | o D |
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264 | Reads a decimal integer into the corresponding |
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265 | <[arg]>: <<(long *arg)>>. |
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266 | |
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267 | o o |
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268 | Reads an octal integer into the corresponding <[arg]>: <<(int *arg)>>. |
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269 | |
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270 | o O |
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271 | Reads an octal integer into the corresponding <[arg]>: <<(long *arg)>>. |
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272 | |
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273 | o u |
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274 | Reads an unsigned decimal integer into the corresponding |
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275 | <[arg]>: <<(unsigned int *arg)>>. |
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276 | |
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277 | o U |
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278 | Reads an unsigned decimal integer into the corresponding <[arg]>: |
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279 | <<(unsigned long *arg)>>. |
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280 | |
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281 | o x,X |
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282 | Read a hexadecimal integer into the corresponding <[arg]>: |
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283 | <<(int *arg)>>. |
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284 | |
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285 | o e, f, g |
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286 | Read a floating-point number into the corresponding <[arg]>: |
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287 | <<(float *arg)>>. |
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288 | |
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289 | o E, F, G |
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290 | Read a floating-point number into the corresponding <[arg]>: |
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291 | <<(double *arg)>>. |
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292 | |
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293 | o i |
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294 | Reads a decimal, octal or hexadecimal integer into the |
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295 | corresponding <[arg]>: <<(int *arg)>>. |
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296 | |
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297 | o I |
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298 | Reads a decimal, octal or hexadecimal integer into the |
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299 | corresponding <[arg]>: <<(long *arg)>>. |
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300 | |
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301 | o n |
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302 | Stores the number of characters read in the corresponding |
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303 | <[arg]>: <<(int *arg)>>. |
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304 | |
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305 | o p |
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306 | Stores a scanned pointer. ANSI C leaves the details |
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307 | to each implementation; this implementation treats |
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308 | <<%p>> exactly the same as <<%U>>. Corresponding |
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309 | <[arg]>: <<(void **arg)>>. |
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310 | o- |
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311 | |
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312 | A <[pattern]> of characters surrounded by square brackets can be used |
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313 | instead of the <<s>> type character. <[pattern]> is a set of |
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314 | characters which define a search set of possible characters making up |
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315 | the <<scanf>> input field. If the first character in the brackets is a |
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316 | caret (<<^>>), the search set is inverted to include all ASCII characters |
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317 | except those between the brackets. There is also a range facility |
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318 | which you can use as a shortcut. <<%[0-9] >> matches all decimal digits. |
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319 | The hyphen must not be the first or last character in the set. |
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320 | The character prior to the hyphen must be lexically less than the |
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321 | character after it. |
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322 | |
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323 | Here are some <[pattern]> examples: |
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324 | o+ |
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325 | o %[abcd] |
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326 | matches strings containing only <<a>>, <<b>>, <<c>>, and <<d>>. |
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327 | |
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328 | o %[^abcd] |
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329 | matches strings containing any characters except <<a>>, <<b>>, |
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330 | <<c>>, or <<d>> |
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331 | |
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332 | o %[A-DW-Z] |
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333 | matches strings containing <<A>>, <<B>>, <<C>>, <<D>>, <<W>>, |
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334 | <<X>>, <<Y>>, <<Z>> |
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335 | |
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336 | o %[z-a] |
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337 | matches the characters <<z>>, <<->>, and <<a>> |
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338 | o- |
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339 | |
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340 | Floating point numbers (for field types <<e>>, <<f>>, <<g>>, <<E>>, |
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341 | <<F>>, <<G>>) must correspond to the following general form: |
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342 | |
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343 | . [+/-] ddddd[.]ddd [E|e[+|-]ddd] |
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344 | |
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345 | where objects inclosed in square brackets are optional, and <<ddd>> |
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346 | represents decimal, octal, or hexadecimal digits. |
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347 | O- |
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348 | |
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349 | RETURNS |
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350 | <<scanf>> returns the number of input fields successfully |
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351 | scanned, converted and stored; the return value does |
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352 | not include scanned fields which were not stored. |
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353 | |
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354 | If <<scanf>> attempts to read at end-of-file, the return |
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355 | value is <<EOF>>. |
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356 | |
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357 | If no fields were stored, the return value is <<0>>. |
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358 | |
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359 | <<scanf>> might stop scanning a particular field before |
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360 | reaching the normal field end character, or may |
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361 | terminate entirely. |
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362 | |
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363 | <<scanf>> stops scanning and storing the current field |
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364 | and moves to the next input field (if any) |
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365 | in any of the following situations: |
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366 | |
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367 | O+ |
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368 | o The assignment suppressing character (<<*>>) appears |
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369 | after the <<%>> in the format specification; the current |
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370 | input field is scanned but not stored. |
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371 | |
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372 | o <[width]> characters have been read (<[width]> is a |
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373 | width specification, a positive decimal integer). |
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374 | |
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375 | o The next character read cannot be converted |
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376 | under the the current format (for example, |
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377 | if a <<Z>> is read when the format is decimal). |
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378 | |
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379 | o The next character in the input field does not appear |
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380 | in the search set (or does appear in the inverted search set). |
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381 | O- |
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382 | |
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383 | When <<scanf>> stops scanning the current input field for one of |
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384 | these reasons, the next character is considered unread and |
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385 | used as the first character of the following input field, or the |
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386 | first character in a subsequent read operation on the input. |
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387 | |
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388 | <<scanf>> will terminate under the following circumstances: |
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389 | |
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390 | O+ |
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391 | o The next character in the input field conflicts |
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392 | with a corresponding non-whitespace character in the |
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393 | format string. |
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394 | |
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395 | o The next character in the input field is <<EOF>>. |
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396 | |
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397 | o The format string has been exhausted. |
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398 | O- |
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399 | |
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400 | When the format string contains a character sequence that is |
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401 | not part of a format specification, the same character |
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402 | sequence must appear in the input; <<scanf>> will |
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403 | scan but not store the matched characters. If a |
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404 | conflict occurs, the first conflicting character remains in the input |
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405 | as if it had never been read. |
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406 | |
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407 | PORTABILITY |
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408 | <<scanf>> is ANSI C. |
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409 | |
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410 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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411 | <<lseek>>, <<read>>, <<sbrk>>, <<write>>. |
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412 | */ |
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413 | |
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414 | #include <_ansi.h> |
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415 | #include <reent.h> |
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416 | #include <stdio.h> |
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417 | #include <string.h> |
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418 | #include <stdarg.h> |
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419 | #include "local.h" |
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420 | |
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421 | #ifndef _REENT_ONLY |
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422 | |
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423 | int |
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424 | sscanf (const char *__restrict str, |
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425 | const char * fmt, ...) |
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426 | { |
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427 | int ret; |
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428 | va_list ap; |
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429 | FILE f; |
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430 | |
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431 | f._flags = __SRD | __SSTR; |
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432 | f._bf._base = f._p = (unsigned char *) str; |
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433 | f._bf._size = f._r = strlen (str); |
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434 | f._read = __seofread; |
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435 | f._ub._base = NULL; |
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436 | f._lb._base = NULL; |
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437 | f._file = -1; /* No file. */ |
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438 | va_start (ap, fmt); |
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439 | ret = __ssvfscanf_r (_REENT, &f, fmt, ap); |
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440 | va_end (ap); |
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441 | return ret; |
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442 | } |
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443 | |
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444 | #ifdef _NANO_FORMATTED_IO |
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445 | int |
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446 | siscanf (const char *, const char *, ...) |
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447 | _ATTRIBUTE ((__alias__("sscanf"))); |
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448 | #endif |
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449 | |
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450 | #endif /* !_REENT_ONLY */ |
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451 | |
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452 | int |
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453 | _sscanf_r (struct _reent *ptr, |
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454 | const char *__restrict str, |
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455 | const char *__restrict fmt, ...) |
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456 | { |
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457 | int ret; |
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458 | va_list ap; |
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459 | FILE f; |
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460 | |
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461 | f._flags = __SRD | __SSTR; |
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462 | f._bf._base = f._p = (unsigned char *) str; |
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463 | f._bf._size = f._r = strlen (str); |
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464 | f._read = __seofread; |
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465 | f._ub._base = NULL; |
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466 | f._lb._base = NULL; |
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467 | f._file = -1; /* No file. */ |
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468 | va_start (ap, fmt); |
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469 | ret = __ssvfscanf_r (ptr, &f, fmt, ap); |
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470 | va_end (ap); |
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471 | return ret; |
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472 | } |
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473 | |
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474 | #ifdef _NANO_FORMATTED_IO |
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475 | int |
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476 | _siscanf_r (struct _reent *, const char *, const char *, ...) |
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477 | _ATTRIBUTE ((__alias__("_sscanf_r"))); |
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478 | #endif |
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