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string(3C)                                             string(3C)



NAME
     strcat, strncat, strcmp, strncmp, strcpy, strncpy, strdup,
     strlen, strchr, strrchr, strpbrk, strspn, strcspn, strstr,
     strtok, index, rindex - 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;

SYNOPSIS (SYSV.3)
     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)



     char *strdup (s1)
     char *s1;

SYNOPSIS (4.2BSD)
     char *index (s, c)
     char *s, c;

     char *rindex (s, c)
     char *s, c;

SYNOPSIS (POSIX)
     char *strstr (s1, s2)
     char *s1, *s2;

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 returns a
     pointer to the null-terminated result.

     Strcmp compares its arguments and returns an integer less
     than, equal to, or greater than 0, according as s1 is lexi-
     cographically 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 char-
     acter 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 returns s1.

     Strdup returns a pointer to a new string which is a dupli-
     cate of the string pointed to by s1.  The space for the new
     string is obtained using malloc(3C).  If the new string can-
     not be created, a NULL pointer is returned.

     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 ter-
     minating 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



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string(3C)                                             string(3C)



     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.

     Strstr locates the first occurence of the string pointed to
     by s2 (excluding the null character) in the string pointed
     at by s1.  It returns a pointer to the located string, or a
     NULL pointer if the string is not found.  If the length of
     the string pointed to by s2 is zero, strstr returns s1.

     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 will have written 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 subsequent calls (which must
     be made with the first argument a NULL pointer) will work
     through the string s1 immediately following that token.  In
     this way subsequent calls will work through the string s1
     until no tokens remain.  The separator string s2 may be dif-
     ferent from call to call.  When no token remains in s1, a
     NULL pointer is returned.

     Index (rindex) 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 ter-
     minating a string is considered to be part of the string.

NOTE
     For user convenience, all these functions are declared in
     the optional <string.h> header file.

BUGS
     Strcmp and strncmp use native character comparison, which is
     unsigned on other machines.  Thus the sign of the value
     returned when one of the characters has its high-order bit
     set is implementation-dependent.

WARNINGS
     Character movement is performed differently in different
     implementations.  Thus overlapping moves may yield
     surprises.









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