Found using sub-string based method
find for a character look-up.
It is more efficient to use the single-character overload when searching for a single character within a std::string, because it avoids the overhead of iterating over character literal. This can be especially important if you are searching for many single characters, as the overhead can add up. This is applicable on the following
std::string search methods :-
std::string message("header"); message.find("a");
std::string message("header"); message.find('a');