string(3C) string(3C)
NAME
strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen,
strchr, strrchr, strpbrk, strspn, strcspn, strtok - string
operations
SYNOPSIS
#include <string.h>
char *strcat (s1, s2)
char *s1, *s2;
char *strncat (s1, s2, n)
char *s1, *s2;
int n;
int strcmp (s1, s2)
char *s1, *s2;
int strncmp (s1, s2, n)
char *s1, *s2;
int n;
char *strcpy (s1, s2)
char *s1, *s2;
char *strncpy (s1, s2, n)
char *s1, *s2;
int n;
int strlen (s)
char *s;
char *strchr (s, c)
char *s;
int c;
char *strrchr (s, c)
char *s;
int c;
char *strpbrk (s1, s2)
char *s1, *s2;
int strspn (s1, s2)
char *s1, *s2;
int strcspn (s1, s2)
char *s1, *s2;
char *strtok (s1, s2)
char *s1, *s2;
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string(3C) string(3C)
DESCRIPTION
The arguments s1, s2, and s point to strings (arrays of
characters terminated by a null character). The functions
strcat, strncat, strcpy, and strncpy all alter s1. These
functions do not check for overflow of the array pointed to
by s1.
strcat appends a copy of string s2 to the end of string s1.
strncat appends at most n characters. Each function returns
a pointer to the null-terminated result.
strcmp performs a lexicographical comparison of its
arguments and returns an integer less than, equal to, or
greater than 0, when s1 is less than, equal to, or greater
than s2, respectively. strncmp makes the same comparison
but looks at a maximum of n characters.
strcpy copies string s2 to string s1, stopping after the
null character has been copied. strncpy copies exactly n
characters, truncating s2 or adding null characters to s1 if
necessary. The result is not null-terminated if the length
of s2 is n or more. Each function returns s1.
strlen returns the number of characters in s, not including
the terminating null character.
strchr (strrchr) returns a pointer to the first (last)
occurrence of character c in string s, or a NULL pointer if
c does not occur in the string. The null character
terminating a string is considered to be part of the string.
strpbrk returns a pointer to the first occurrence in string
s1 of any character from string s2, or a NULL pointer if no
character from s2 exists in s1.
strspn (strcspn) returns the length of the initial segment
of string s1 which consists entirely of characters from (not
from) string s2.
strtok considers the string s1 to consist of a sequence of
zero or more text tokens separated by spans of one or more
characters from the separator string s2. The first call
(with pointer s1 specified) returns a pointer to the first
character of the first token, and writes a null character
into s1 immediately following the returned token. The
function keeps track of its position in the string between
separate calls, so that on subsequent calls (which must be
made with a NULL pointer as the first argument) it works
through the string s1 immediately following that token.
This can be continued until no tokens remain. The separator
string s2 may be different from call to call. When no token
remains in s1, a NULL pointer is returned.
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string(3C) string(3C)
NOTE
For user convenience, all these functions are declared in
the optional <string.h> header file.
BUGS
strcmp use native character comparison. Thus the sign of
the value returned when one of the characters has its high-
order bit set is implementation-dependent.
All string movement is performed character by character
starting at the left. Thus overlapping moves toward the
left will work as expected, but overlapping moves to the
right may yield surprises.
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