Copyright (c) 1980 Regents of the University of California.
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@(#)string.3 6.1 (Berkeley) 05/15/85

C 4 strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, index, rindex - string operations

 #include <strings.h> 

 char *strcat(s1, s2)  char *s1, *s2; 

 char *strncat(s1, s2, n)  char *s1, *s2; 

 strcmp(s1, s2)  char *s1, *s2; 

 strncmp(s1, s2, n)  char *s1, *s2; 

 char *strcpy(s1, s2)  char *s1, *s2; 

 char *strncpy(s1, s2, n)  char *s1, *s2; 

 strlen(s)  char *s; 

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

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

These functions operate on null-terminated strings. They do not check for overflow of any receiving string.

Strcat appends a copy of string s2 to the end of string s1 . Strncat copies at most n characters. Both return a pointer to the null-terminated result.

Strcmp compares its arguments and returns an integer greater than, equal to, or less than 0, according as s1 is lexicographically greater than, equal to, or less 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 moved. Strncpy copies exactly n characters, truncating or null-padding s2; the target may not be null-terminated if the length of s2 is n or more. Both return s1 .

Strlen returns the number of non-null characters in s .

Index ( rindex ) returns a pointer to the first (last) occurrence of character c in string s, or zero if c does not occur in the string.