casecmp(3) - phpMan

strcasecmp (3)       - compare two strings ignoring case
strcasecmp (3p)      - case-insensitive string comparisons
strncasecmp (3)      - compare two strings ignoring case
strncasecmp (3p)     - case-insensitive string comparisons
wcscasecmp (3)       - compare two wide-character strings, ignoring case
wcsncasecmp (3)      - compare two fixed-size wide-character strings, ignorin...