man3/string.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" References consulted:
   6 .\"     Linux libc source code
   7 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
   8 .\"     386BSD man pages
   9 .\" Modified Sun Jul 25 10:54:31 1993, Rik Faith (faith@cs.unc.edu)
  10 .TH STRING 3 2021-03-22 "Linux man-pages (unreleased)"
  11 .SH NAME
  12 stpcpy, strcasecmp, strcat, strchr, strcmp, strcoll, strcpy, strcspn,
  13 strdup, strfry, strlen, strncat, strncmp, strncpy, strncasecmp, strpbrk,
  14 strrchr, strsep, strspn, strstr, strtok, strxfrm, index, rindex
  15 \- string operations
  16 .SH LIBRARY
  17 Standard C library
  18 .RI ( libc ", " \-lc )
  19 .SH SYNOPSIS
  20 .B #include <strings.h>
  21 .TP
  22 .BI "int strcasecmp(const char *" s1 ", const char *" s2 );
  23 Compare the strings
  24 .I s1
  25 and
  26 .I s2
  27 ignoring case.
  28 .TP
  29 .BI "int strncasecmp(const char *" s1 ", const char *" s2 ", size_t " n );
  30 Compare the first
  31 .I n
  32 bytes of the strings
  33 .I s1
  34 and
  35 .I s2
  36 ignoring case.
  37 .TP
  38 .BI "char *index(const char *" s ", int " c );
  39 Return a pointer to the first occurrence of the character
  40 .I c
  41 in the string
  42 .IR s .
  43 .TP
  44 .BI "char *rindex(const char *" s ", int " c );
  45 Return a pointer to the last occurrence of the character
  46 .I c
  47 in the string
  48 .IR s .
  49 .TP
  50 .B #include <string.h>
  51 .TP
  52 .BI "char *stpcpy(char *restrict " dest ", const char *restrict " src );
  53 Copy a string from
  54 .I src
  55 to
  56 .IR dest ,
  57 returning a pointer to the end of the resulting string at
  58 .IR dest .
  59 .TP
  60 .BI "char *strcat(char *restrict " dest ", const char *restrict " src );
  61 Append the string
  62 .I src
  63 to the string
  64 .IR dest ,
  65 returning a pointer
  66 .IR dest .
  67 .TP
  68 .BI "char *strchr(const char *" s ", int " c );
  69 Return a pointer to the first occurrence of the character
  70 .I c
  71 in the string
  72 .IR s .
  73 .TP
  74 .BI "int strcmp(const char *" s1 ", const char *" s2 );
  75 Compare the strings
  76 .I s1
  77 with
  78 .IR s2 .
  79 .TP
  80 .BI "int strcoll(const char *" s1 ", const char *" s2 );
  81 Compare the strings
  82 .I s1
  83 with
  84 .I s2
  85 using the current locale.
  86 .TP
  87 .BI "char *strcpy(char *restrict " dest ", const char *restrict " src );
  88 Copy the string
  89 .I src
  90 to
  91 .IR dest ,
  92 returning a pointer to the start of
  93 .IR dest .
  94 .TP
  95 .BI "size_t strcspn(const char *" s ", const char *" reject );
  96 Calculate the length of the initial segment of the string
  97 .I s
  98 which does not contain any of bytes in the string
  99 .IR reject ,
 100 .TP
 101 .BI "char *strdup(const char *" s );
 102 Return a duplicate of the string
 103 .I s
 104 in memory allocated using
 105 .BR malloc (3).
 106 .TP
 107 .BI "char *strfry(char *" string );
 108 Randomly swap the characters in
 109 .IR string .
 110 .TP
 111 .BI "size_t strlen(const char *" s );
 112 Return the length of the string
 113 .IR s .
 114 .TP
 115 .BI "char *strncat(char *restrict " dest ", const char *restrict " src \
 116 ", size_t " n );
 117 Append at most
 118 .I n
 119 bytes from the string
 120 .I src
 121 to the string
 122 .IR dest ,
 123 returning a pointer to
 124 .IR dest .
 125 .TP
 126 .BI "int strncmp(const char *" s1 ", const char *" s2 ", size_t " n );
 127 Compare at most
 128 .I n
 129 bytes of the strings
 130 .I s1
 131 and
 132 .IR s2 .
 133 .TP
 134 .BI "char *strncpy(char *restrict " dest ", const char *restrict " src \
 135 ", size_t " n );
 136 Copy at most
 137 .I n
 138 bytes from string
 139 .I src
 140 to
 141 .IR dest ,
 142 returning a pointer to the start of
 143 .IR dest .
 144 .TP
 145 .BI "char *strpbrk(const char *" s ", const char *" accept );
 146 Return a pointer to the first occurrence in the string
 147 .I s
 148 of one of the bytes in the string
 149 .IR accept .
 150 .TP
 151 .BI "char *strrchr(const char *" s ", int " c );
 152 Return a pointer to the last occurrence of the character
 153 .I c
 154 in the string
 155 .IR s .
 156 .TP
 157 .BI "char *strsep(char **restrict " stringp ", const char *restrict " delim );
 158 Extract the initial token in
 159 .I stringp
 160 that is delimited by one of the bytes in
 161 .IR delim .
 162 .TP
 163 .BI "size_t strspn(const char *" s ", const char *" accept );
 164 Calculate the length of the starting segment in the string
 165 .I s
 166 that consists entirely of bytes in
 167 .IR accept .
 168 .TP
 169 .BI "char *strstr(const char *" haystack ", const char *" needle );
 170 Find the first occurrence of the substring
 171 .I needle
 172 in the string
 173 .IR haystack ,
 174 returning a pointer to the found substring.
 175 .TP
 176 .BI "char *strtok(char *restrict " s ", const char *restrict " delim );
 177 Extract tokens from the string
 178 .I s
 179 that are delimited by one of the bytes in
 180 .IR delim .
 181 .TP
 182 .BI "size_t strxfrm(char *restrict " dst ", const char *restrict " src \
 183 ", size_t " n );
 184 Transforms
 185 .I src
 186 to the current locale and copies the first
 187 .I n
 188 bytes to
 189 .IR dst .
 190 .SH DESCRIPTION
 191 The string functions perform operations on null-terminated
 192 strings.
 193 See the individual man pages for descriptions of each function.
 194 .SH SEE ALSO
 195 .BR bstring (3),
 196 .BR index (3),
 197 .BR rindex (3),
 198 .BR stpcpy (3),
 199 .BR strcasecmp (3),
 200 .BR strcat (3),
 201 .BR strchr (3),
 202 .BR strcmp (3),
 203 .BR strcoll (3),
 204 .BR strcpy (3),
 205 .BR strcspn (3),
 206 .BR strdup (3),
 207 .BR strfry (3),
 208 .BR strlen (3),
 209 .BR strncasecmp (3),
 210 .BR strncat (3),
 211 .BR strncmp (3),
 212 .BR strncpy (3),
 213 .BR strpbrk (3),
 214 .BR strrchr (3),
 215 .BR strsep (3),
 216 .BR strspn (3),
 217 .BR strstr (3),
 218 .BR strtok (3),
 219 .BR strxfrm (3)