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STRING(3)                  Library Functions Manual                  STRING(3)



NAME
       strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, str‐
       rchr, strpbrk, strspn, strcspn, strtok, index, rindex -  string  opera‐
       tions

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;

       char *strdup(s)
       char *s;

DESCRIPTION
       The arguments s1, s2 and s point to null-terminated strings.  The func‐
       tions strcat, strncat, strcpy, and strncpy all alter s1.   These  func‐
       tions 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 returns a pointer to the  null-ter‐
       minated result.

       Strcmp  compares  its arguments and returns an integer less than, equal
       to, or greater than 0, according as s1 is lexicographically less  than,
       equal  to,  or  greater than s2.  Strncmp makes the same comparison but
       looks at at most n characters.

       Strcpy copies string s2 to 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  will  not  be
       null-terminated  if  the  length of s2 is n or more.  Each function re‐
       turns s1.

       Strlen returns the number of characters in s, not including the  termi‐
       nating null character.

       Strchr  (strrchr)  returns  a pointer to the first (last) occurrence of
       character c in string s, or 0 if c does not occur in the  string.   The
       null  character  terminating  a  string is considered to be part of the
       string.  Index and rindex are obsolete names for strchr and strrchr.

       Strpbrk returns a pointer to the first occurrence in string s1  of  any
       character from string s2, 0 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 sepa‐
       rator string s2.  The first call, with pointer s1 specified, returns  a
       pointer  to the first character of the first token, and will have writ‐
       ten a null character into s1 immediately following the returned  token.
       The function keeps track of its position in the string between separate
       calls; subsequent calls, signified by s1 being 0, will work through the
       string  s1  immediately  following that token.  The separator string s2
       may be different from call to call.  When no token remains in s1, 0  is
       returned.

       Strdup  returns  a  pointer  to  a distinct copy of the null-terminated
       string s in space obtained from malloc(3) or 0 if no space can  be  ob‐
       tained.

SEE ALSO
       memory(3)

BUGS
       Strcmp  and strncmp use native character comparison, which is signed on
       some machines, unsigned on others, but consistent on ASCII characters.
       The outcome of overlapping moves varies among implementations.



                                                                     STRING(3)