strstr - find a substring
char *strstr(const char *s1, const char *s2);
[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.1-2017 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.
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.
No errors are defined.
First released in Issue 3. Included for alignment with the ANSI C standard.
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