strnstr

Locate a substring in a string

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Contents

Interface
Description
Return Values
See Also
Standards
Page Comments

Interface

#include <string.h>char  strstr (const char *big, const char *little)
char  strcasestr (const char *big, const char *little)
char  strnstr (const char *big, const char *little, size_t len)

#include <xlocale.h>char  strcasestr_l (const char *big, const char *little, locale_t loc)

Description

The strstr function locates the first occurrence of the null-terminated string \c little in the null-terminated string \c big.

The strcasestr function is similar to strstr , but ignores the case of both strings.

The strnstr function locates the first occurrence of the null-terminated string \c little in the string \c big, where not more than \c len characters are searched. Characters that appear after a \0 character are not searched. Since the strnstr function is a FreeBSD specific API, it should only be used when portability is not a concern.

While the strcasestr function uses the current locale, the strcasestr_l function may be passed a locale directly. See xlocale for more information.

Return Values

If little is an empty string, big is returned; if little occurs nowhere in big, NULL is returned; otherwise a pointer to the first character of the first occurrence of little is returned.

Example:

Example - Locate a substring in a string

Problem

The following sets the pointer ptr to the "Bar Baz" portion of largestring:

Workings

const char *largestring = "Foo Bar Baz";
const char *smallstring = "Bar";
char *ptr;
 
ptr = strstr(largestring, smallstring);

Standards

The strstr function conforms to ISO/IEC 9899:1990 ("ISO C90").

char	`strstr` (const char big, const char little)
char	`strcasestr` (const char big, const char little)
char	`strnstr` (const char big, const char little, size_t len)