July 3, 2004 STRSTR 3

### NAME

strstr,strcasestr - locate a substring in a string

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```char``*` strstr(```const char *big``, const char *little`)
```char``*` strcasestr(```const char *big``, const char *little`)

### 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.

### 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'') .