How to convert a string variable containing time to time_t type in c++?

Question

I have a string variable containing time in hh:mm:ss format. How to convert it into time_t type? eg: string time_details = "16:35:12"

Also, how to compare two variables containing time so as to decide which is the earliest? eg : string curr_time = "18:35:21" string user_time = "22:45:31"

Answer 1

With C++11 you can now do

struct std::tm tm;
std::istringstream ss("16:35:12");
ss >> std::get_time(&tm, "%H:%M:%S"); // or just %T in this case
std::time_t time = mktime(&tm);

see std::get_time and strftime for reference