strcasestr() - case-insensitive search for substring in a string
#include <strings.h>
char *strcasestr(const char *s, const char *find)
The strcasestr(3) function searches the string s, ignoring case, to find the first occurrence of the string find.
On success, the strcasestr(3) function returns a pointer to the first occurrence of the substring find. On failure, it returns NULL.
strstr(3)
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