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How to convert string to number in C++

📅 2014-Sep-17 ⬩ ✍️ Ashwin Nanjappa ⬩ 🏷️ cpp, float, int, stof, stoi, string ⬩ 📚 Archive

In C+11 and later versions, a string containing an integer or floating point value can be converted easily to its numeric value. To do this, use the stoi, stof and similar functions defined in the string header file. These functions throw an exception on encountering a malformed string and so are recommended over the old C atoi and atof functions.

This example demonstrates this:

#include <iostream>
#include <string>

int main()
    std::string si = "98765";
    std::string sf = "3.14";

    int i = std::stoi(si);
    float f = std::stof(sf);

    std::cout << i << " " << f << std::endl;

    return 0;

Tried with: GCC 4.9.1 and Ubuntu 14.04