string(3C) string(3C)
NAME
string: strcat, strncat, strcmp, strncmp, strcpy, strncpy,
strdup, strlen, strchr, strrchr, strpbrk, strspn, strcspn,
strtok, strtok_r, strstr - string operations
SYNOPSIS
#include <string.h>
char *strcat(char *s1, const char *s2);
char *strncat(char *s1, const char *s2, size_t n);
int strcmp(const char *s1, const char *s2);
int strncmp(const char *s1, const char *s2, size_t n);
char *strcpy(char *s1, const char *s2);
char *strncpy(char *s1, const char *s2, size_t n);
char *strdup(const char *s1);
size_t strlen(const char *s);
char *strchr(const char *s, int c);
char *strrchr(const char *s, int c);
char *strpbrk(const char *s1, const char *s2);
size_t strspn(const char *s1, const char *s2);
size_t strcspn(const char *s1, const char *s2);
char *strtok(char *s1, const char *s2);
char *strtok_r(char *s1, const char *s2, char **next);
char *strstr(const char *s1, const char *s2);
DESCRIPTION
The arguments s, s1, and s2 point to strings (arrays of
characters terminated by a null character). The functions
strcat, strncat, strcpy, strncpy, strtok, and strtok_r alter
s1. These functions do not check for overflow of the array
pointed to by s1.
strcat appends a copy of string s2, including the terminating
null character, to the end of string s1. strncat appends at
most n characters. Each returns a pointer to the null-
terminated result. The initial character of s2 overrides the
null character at the end of s1.
strcmp compares its arguments and returns an integer less
than, equal to, or greater than 0, based upon whether s1 is
lexicographically less than, equal to, or greater than s2.
strncmp makes the same comparison but looks at most n
characters. Characters following a null character are not
compared.
Copyright 1994 Novell, Inc. Page 1
string(3C) string(3C)
strcpy copies string s2 to s1 including the terminating null
character, 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 returns s1.
strdup returns a pointer to a new string which is a duplicate
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 (or strrchr) returns a pointer to the first (last)
occurrence of c (converted to a char) 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 (or strcspn) returns the length of the initial segment
of string s1 which consists entirely of characters from (not
from) string s2.
strtok_r 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 non-null) returns a pointer to the first character
of the first token, will have written a null character into s1
immediately following the returned token and will save in the
object pointed to by next information sufficient to continue
tokenizing the same string in subsequent calls. To continue
with the same string, s1 should be a null pointer, and the
object pointed to by next should not be modified. 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.
strtok behaves just like strtok_r except that it remembers its
own position within a single string, s1, instead of using a
provided object (as is pointed to by next with strtok_r).
Copyright 1994 Novell, Inc. Page 2
string(3C) string(3C)
strstr locates the first occurrence in string s1 of the
sequence of characters (excluding the terminating null
character) in string s2. strstr returns a pointer to the
located string, or a null pointer if the string is not found.
If s2 points to a string with zero length (that is, the string
""), the function returns s1.
REFERENCES
malloc(3C), setlocale(3C), strxfrm(3C)
NOTICES
All of these functions assume the default locale ``C.'' For
some locales, strxfrm should be applied to the strings before
they are passed to the functions.
The reentrant version, strtok_r, is recommended for multi-
threaded applications.
Copyright 1994 Novell, Inc. Page 3