C Programming/string.h/strstr

strstr is a C standard library string function as defined in string.h. strstr has the function signature char * strstr(const char *haystack, const char *needle); which returns a pointer to a character at the first index where needle is in haystack, or NULL if not present.

The strcasestr is a function much like strstr except that it ignores the case of both <tt>needle</tt> and <tt>haystack</tt>. <tt>strcasestr</tt> is a non-standard function while <tt>strstr</tt> conforms to C89 and C99.

Example
<tt>cptr</tt> is now a pointer to the sixth letter (<tt>e</tt>) in "wikipedia".