How do I ignore a string case?

Compare Two Strings Ignoring the Case in C++

equalsIgnoreCase() method compares this String to another String, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length and corresponding characters in the two strings are equal ignoring case.

The strcasecmp() function performs a byte-by-byte comparison of the strings s1 and s2, ignoring the case of the characters . It returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2.16 Mar 2015

std::string provides a method std::string::find to search for the sub string inside a given string, but this function is case sensitive i.e. std::string data = “Hi this is a sample string”; size_t pos = data.