How can I convert a std::string to int?

Question

Just have a quick question. I\'ve looked around the internet quite a bit and I\'ve found a few solutions but none of them have worked yet. Looking at converting a string to

Answer 1

One line version: long n = strtol(s.c_str(), NULL, base); .

(s is the string, and base is an int such as 2, 8, 10, 16.)

You can refer to this link for more details of strtol.

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The core idea is to use strtol function, which is included in cstdlib.

Since strtol only handles with char array, we need to convert string to char array. You can refer to this link.

An example:

#include <iostream>
#include <string>   // string type
#include <bitset>   // bitset type used in the output

int main(){
    s = "1111000001011010";
    long t = strtol(s.c_str(), NULL, 2); // 2 is the base which parse the string

    cout << s << endl;
    cout << t << endl;
    cout << hex << t << endl;
    cout << bitset<16> (t) << endl;

    return 0;
}

which will output:

1111000001011010
61530
f05a
1111000001011010