curl_strequal(3) -- Linux man page
NAMEcurl_strequal, curl_strnequal - case insensitive string comparisons
int curl_strequal(char *str1, char *str2);
DESCRIPTIONThe curl_strequal() function compares the two strings str1 and str2, ignoring the case of the characters. It returns a non-zero (TRUE) integer if the strings are identical.
The curl_strnequal() function is similar, except it only compares the first len characters of str1.
These functions are provided by libcurl to enable applications to compare strings in a truly portable manner. There are no standard portable case insensitive string comparison functions. These two works on all platforms.
AVAILABILITYThese functions will be removed from the public libcurl API in a near future. They will instead be made "available" by source code access only, and then as curlx_strequal() and curlx_strenqual().
RETURN VALUENon-zero if the strings are identical. Zero if they're not.
SEE ALSOstrcmp(3), strcasecmp(3)