split a C++ string into two integers, which are delimited by ":"

Question

I have a string like this:

string str = "18:10";

18 is the minutes and 10 is the seconds. I need to split the string str and store them into two int variables. So essentially like this: int a = 18, int b =10. How do I do that?

[Check this one](http://stackoverflow.com/a/236803/6021126), then use std::stoi. — Andrii Bakal, Mar 05 '16 at 05:47
Have you tried anything yourself? It seems like you just want community to do the job for you. — MarengoHue, Mar 05 '16 at 06:22
I'm new with C++, I use python a lot, I just switched to C++. In python, I can just do str.split(":"). — JY078, Mar 05 '16 at 06:33
i'm so sorry,of course I tried myself. I tried: string str = "18:10"; istringstream iss(str); int n; while(iss>n) { int a; int b; cin >> a >>b;}. And it did not work. lol — JY078, Mar 05 '16 at 06:43

score 3 · Accepted Answer · answered Mar 05 '16 at 05:48

There's a few way to do this, C style (atoi, atof etc). In C++ we'd use std::stringstream from the header sstream.

#include <iostream>
#include <sstream>

template <typename T>
T convertString( std::string str ) {
    T ret;
    std::stringstream ss(str);
    ss >> ret;
    return ret;
}

int main() {
    std::string str = "18:10";
    int minutes,seconds;

    minutes = convertString<int>(str.substr(0,2));
    seconds = convertString<int>(str.substr(3,4));

    std::cout<<minutes<<" "<<seconds<<"\n";
}

Output:

18 10

This, of course, assumes that your string follow this format exactly (same number of integers, seperated by colon..). If you need to use this in a wider context, perhaps you'd be interested in using the std::regex utility instead.

I wonder why you have the template? Could this work for other types as well such as `float` and `double`? — smttsp, Mar 05 '16 at 05:56
@smttsp I believe so, looking at http://www.cplusplus.com/reference/istream/istream/operator%3E%3E/, _"Extracts and parses characters sequentially from the stream to interpret them as the representation of a value of the proper type, which is stored as the value of val...."_. Correct me if I'm wrong. — 058 094 041, Mar 05 '16 at 05:58

hkBattousai · Answer 2 · 2016-03-05T06:00:18.590

Try this code.

#include <string>
#include <sstream>

template <class NumberType, class CharType>
NumberType StringToNumber(const std::basic_string<CharType> & String)
{
    std::basic_istringstream<CharType> Stream(String);
    NumberType Number;
    Stream >> Number;
    return Number;
}

const std::string str("18:10");
const size_t Pos = str.find(':');
const auto Hour = StringToNumber<int>(str.substr(0, Pos));
const auto Minute = StringToNumber<int>(str.substr(Pos + 1, std::string::npos));

I didn't test it. Fix it if there is any error. You have to do error handling if your string may have empty parts for hours or minutes (e.g.; ":10", "18:" or ":").

you don't have to worry about error handling, all strings have mins and secs — JY078, Mar 05 '16 at 05:58

split a C++ string into two integers, which are delimited by ":"

2 Answers2

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