string(3)

NAME

strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, strrchr, strpbrk, strspn, strcspn, strtok, index, rindex − string operations

SYNTAX

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

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

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

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;

strlen(s)
char *s;

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

char *rindex(s, c)
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;

DESCRIPTION

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

The strcat subroutine appends a copy of string s2 to the end of string s1. The strncat subroutine copies, at most, n characters. Both return a pointer to the null-terminated result.

The strcmp subroutine 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. The strncmp subroutine makes the same comparison but looks at at most n characters.

The strcpy subroutine copies string s2 to s1, stopping after the null character has been moved. The strncpy subroutine 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.

The strlen subroutine returns the number of non-null characters in s.

The index and rindex subroutines return a pointer to the first and last occurrence of character c, respectively, in string s, or zero if c does not occur in the string.

The strchr and strrchr subroutines return a pointer to the first and last occurrence of character c, respectively, 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.

The strpbrk subroutine 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.

The strspn and strcspn subroutines return the length of the initial segment of string s1 which consists entirely of characters from (not from) string s2.

The strtok subroutine 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 different from call to call. When no token remains in s1, a NULL pointer is returned.

NOTE

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

RESTRICTIONS