STRSTR(3) | Library Functions Manual | STRSTR(3)

# NAME

`strstr`, `strcasestr`, `strnstr` —
locate a substring in a string

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

`#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);

# DESCRIPTION

The `strstr`() function locates the first occurrence of the nul-terminated string little in the nul-terminated string big.

The `strcasestr`() function is similar to `strstr`(), but ignores the case of both strings. The `strnstr`() function locates the first occurrence of the NUL-terminated string little in the string big, where not more than len characters are searched. Characters that appear after a ‘`\0`’ character are not searched. Since the `strnstr`() function is a NetBSD specific API, it should only be used when portability is not a concern.

# 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.

# EXAMPLES

The following sets the pointer ptr to the “`Bar Baz`” portion of largestring:

    const char *largestring = "Foo Bar Baz";
    const char *smallstring = "Bar";
    char *ptr;

    ptr = strstr(largestring, smallstring);

# SEE ALSO

index(3), memchr(3), rindex(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strtok(3)

# STANDARDS

The `strstr`() function conforms to ISO/IEC 9899:1990 (“ISO C90”).

# HISTORY

The `strnstr`() function originated in FreeBSD.

September 24, 2014 | NetBSD 9.4