| 1 | .\" Copyright (c) 1980 Regents of the University of California.
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| 2 | .\" All rights reserved. The Berkeley software License Agreement
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| 3 | .\" specifies the terms and conditions for redistribution.
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| 4 | .\"
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| 5 | .\" @(#)string.3 6.1 (Berkeley) 5/15/85
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| 6 | .\"
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| 7 | .TH STRING 3 "May 15, 1985"
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| 8 | .UC 4
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| 9 | .SH NAME
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| 10 | string, strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, strrchr, strerror, memcmp, memcpy, memmove, memchr, memset, index, rindex \- string operations
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| 11 | .SH SYNOPSIS
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| 12 | .nf
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| 13 | .ft B
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| 14 | #include <string.h>
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| 15 |
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| 16 | char *strcat(char *\fIs1\fP, const char *\fIs2\fP)
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| 17 | char *strncat(char *\fIs1\fP, const char *\fIs2\fP, size_t \fIn\fP)
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| 18 | int strcmp(const char *\fIs1\fP, const char *\fIs2\fP)
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| 19 | int strncmp(const char *\fIs1\fP, const char *\fIs2\fP, size_t \fIn\fP)
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| 20 | char *strcpy(char *\fIs1\fP, const char *\fIs2\fP)
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| 21 | char *strncpy(char *\fIs1\fP, const char *\fIs2\fP, size_t \fIn\fP)
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| 22 | size_t strlen(const char *\fIs\fP)
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| 23 | char *strchr(const char *\fIs\fP, int \fIc\fP)
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| 24 | char *strrchr(const char *\fIs\fP, int \fIc\fP)
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| 25 | char *strerror(int \fIerrnum\fP)
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| 26 | int memcmp(const void *\fIs1\fP, const void *\fIs2\fP, size_t \fIn\fP)
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| 27 | void *memcpy(void *\fIs1\fP, const void *\fIs2\fP, size_t \fIn\fP)
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| 28 | void *memmove(void *\fIs1\fP, const void *\fIs2\fP, size_t \fIn\fP)
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| 29 | void *memchr(const void *\fIs\fP, int \fIc\fP, size_t \fIn\fP)
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| 30 | void *memset(void *\fIs\fP, int \fIc\fP, size_t \fIn\fP)
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| 31 | char *index(const char *\fIs\fP, int \fIc\fP)
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| 32 | char *rindex(const char *\fIs\fP, int \fIc\fP)
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| 33 | .ft R
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| 34 | .fi
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| 35 | .SH DESCRIPTION
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| 36 | These functions operate on null-terminated strings.
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| 37 | They do not check for overflow of any receiving string.
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| 38 | .PP
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| 39 | .B Strcat
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| 40 | appends a copy of string
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| 41 | .I s2
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| 42 | to the end of string
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| 43 | .IR s1 .
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| 44 | .B Strncat
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| 45 | copies at most
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| 46 | .I n
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| 47 | characters. Both return a pointer to the null-terminated result.
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| 48 | .PP
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| 49 | .B Strcmp
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| 50 | compares its arguments and returns an integer
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| 51 | greater than, equal to, or less than 0, according as
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| 52 | .I s1
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| 53 | is lexicographically greater than, equal to, or less than
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| 54 | .IR s2 .
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| 55 | .B Strncmp
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| 56 | makes the same comparison but looks at at most
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| 57 | .I n
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| 58 | characters.
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| 59 | .PP
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| 60 | .B Strcpy
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| 61 | copies string
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| 62 | .I s2
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| 63 | to
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| 64 | .IR s1 ,
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| 65 | stopping after the null character has been moved.
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| 66 | .B Strncpy
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| 67 | copies exactly
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| 68 | .I n
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| 69 | characters, truncating or null-padding
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| 70 | .I s2;
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| 71 | the target may not be null-terminated if the length of
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| 72 | .I s2
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| 73 | is
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| 74 | .I n
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| 75 | or more. Both return
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| 76 | .IR s1 .
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| 77 | .PP
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| 78 | .B Strlen
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| 79 | returns the number of non-null characters in
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| 80 | .IR s .
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| 81 | .PP
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| 82 | .B Strchr
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| 83 | .RB ( strrchr )
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| 84 | returns a pointer to the first (last) occurrence of character
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| 85 | .I c
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| 86 | in string
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| 87 | .I s,
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| 88 | or null if
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| 89 | .I c
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| 90 | does not occur in the string.
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| 91 | .PP
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| 92 | .B Strerror
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| 93 | returns the error string for the system call error
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| 94 | .IR errnum .
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| 95 | See
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| 96 | .BR intro (2).
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| 97 | .PP
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| 98 | .B Memcmp
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| 99 | is like
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| 100 | .B strcmp
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| 101 | except that the strings are memory blocks of length
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| 102 | .IR n .
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| 103 | Null characters are treated as ordinary characters.
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| 104 | .PP
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| 105 | .B Memcpy
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| 106 | copies
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| 107 | .I n
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| 108 | bytes from the location pointed to by
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| 109 | .I s2
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| 110 | to
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| 111 | .IR s1 .
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| 112 | .B Memmove
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| 113 | is like memcpy, except that it can handle overlap between the two strings.
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| 114 | Both functions return
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| 115 | .IR s1 .
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| 116 | .PP
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| 117 | .B Memchr
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| 118 | returns a pointer to the first occurrence of character
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| 119 | .I c
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| 120 | in string
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| 121 | .I s,
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| 122 | or null if
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| 123 | .I c
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| 124 | does not occur in the string.
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| 125 | .PP
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| 126 | .B Memset
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| 127 | sets
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| 128 | .I n
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| 129 | bytes to
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| 130 | .I c
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| 131 | starting at location
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| 132 | .IR s .
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| 133 | It returns
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| 134 | .IR s .
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| 135 | .PP
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| 136 | .B Index
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| 137 | and
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| 138 | .B rindex
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| 139 | are obsolete versions of
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| 140 | .B strchr
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| 141 | and
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| 142 | .BR strrchr .
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| 143 | New code should avoid using them.
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| 144 | .SH NOTES
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| 145 | Characters are compared as
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| 146 | .BR "unsigned char" ,
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| 147 | whether
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| 148 | .B char
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| 149 | itself is signed or not.
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