How to convert formatted string HH:MM:SS to seconds in C++

Question

I want to convert a string time stamp formatted in HH:MM:SS to seconds only, and then compare it with a number. I have written a prime version of my code in Java, however I separately ask from Scanner as opposed to having a string time. I'm not much familiar with C++ libraries, as I'm a Java guy. Wondering how I can do it in C++?

Make it brief, String s = "1:01:01"; and String s2= "3600"; I need to know if (s>s2)

import java.util.*;

public class Test {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);

        int hours;
        int mins;
        int secs;

        System.out.println("Enter Hours: ");
        hours = console.nextInt();

        System.out.println("Enter Minutes: ");
        mins = console.nextInt();

        System.out.println("Enter Seconds: ");
        secs = console.nextInt();

        int showSecs = (hours * 3600) + (mins * 60) + secs;

        System.out.println(hours + ":" + mins + ":" + secs + " in secs are "
                + showSecs);

    }
}

Answer 1

I'll risk the downvotes and remind you that we still have sscanf in our toolbox.

int h, m, s= 0;
std::string time ="10:40:03"

if (sscanf(time.c_str(), "%d:%d:%d", &h, &m, &s) >= 2)
{
  int secs = h *3600 + m*60 + s;
}

Answer 2

As @ghostofstandardspast suggested you can use the std::get_time() I/O manipulator to read a specific time format from a std::istream

#include <iostream>
#include <sstream>
#include <locale>
#include <iomanip>
#include <ctime>

int main() {
    std::tm t;
    std::istringstream ss("1:01:01");
    ss >> std::get_time(&t, "%H:%M:%S");
    std::cout << "Total seconds: " 
              << t.tm_hour * 3600 + t.tm_min * 60 + t.tm_sec 
              << std::endl;
}

Here's a fully working sample using clang. Unfortunately I couldn't get this sample running using GCC 4.8.x, I'd guess it's not complete in this implementation. May be GCC 4.9.x supports this correctly.

---

As looking for an alternative (if you can't use a compiler supporting the complete current c++11 standard actually), you may either consider to use std::sscanf() as @Roddy suggested, or split the string using ':' as delimiter character, and simply convert the split out parts to integer values, using the e.g. the atoi() method.
Here's the alternative

#include <iostream>
#include <vector>
#include <string>
#include <sstream>

std::vector<std::string> &split
    ( const std::string &s
    , char delim
    , std::vector<std::string> &elems) 
{
    std::istringstream ss(s);
    std::string item;
    while (std::getline(ss, item, delim)) {
        elems.push_back(item);
    }
    return elems;
}

int main() {
    std::vector<std::string> parts;
    split("1:01:01",':',parts);
    if(parts.size() == 3) {
        int hour = std::atoi(parts[0].c_str());
        int min = std::atoi(parts[1].c_str());
        int sec = std::atoi(parts[2].c_str());
        std::cout << "Total seconds: " 
                  << hour * 3600 + min * 60 + sec 
                  << std::endl; 
    }
    return 0;
}