NAME
strstr — find a
substring
SYNOPSIS
#include
<string.h>
char *strstr(const char *s1, const char *s2);
DESCRIPTION
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.
The strstr () function shall locate the
first occurrence in the string pointed to by s1 of the
sequence of bytes (excluding the terminating NUL character) in the string
pointed to by s2.
[CX] The strstr ()
function shall not change the setting of errno on valid
input.
RETURN VALUE
Upon successful completion, strstr ()
shall return 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, the function shall return s1.
ERRORS
No errors are defined.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
XBD <string.h>
CHANGE HISTORY
First released in Issue 3. Included for alignment with the ANSI C standard.
Issue 8
Austin Group Defect 448 is applied, adding a requirement that
strstr () does not change the setting of
errno on valid input.
Austin Group Defect 1061 is applied, adding memmem(3) to the SEE ALSO section.