strstr3p
Find a substring
Usage
#include <string.h>
char *strstr(const char *s1, const char *s2);
Prolog
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
Overview
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.1‐2017 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.
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.
The following sections are informative.
Examples
None.
Application usage
None.
Rationale
None.
Future directions
None.