how to transfer a string into number c++ code example

Example 1: string to int c++

#include <iostream>
#include <string>

int main() {

    std::string str = "123";
    int num;

    // using stoi() to store the value of str1 to x
    num = std::stoi(str);

    std::cout << num;

    return 0;
}

Example 2: string to int in c++

#include <iostream>
#include <string>
using namespace std;
int main() {
 
    string s = "10";
 
    try
    {
        int i = stoi(s);
        cout << i << '\n';
    }
    catch (invalid_argument const &e)
    {
        cout << "Bad input: std::invalid_argument thrown" << '\n';
    }
    catch (out_of_range const &e)
    {
        cout << "Integer overflow: std::out_of_range thrown" << '\n';
    }
 
    return 0;
}

Example 3: string to int c++

// Both functions work identically though you'll need to use "#include <string>" 
atoi( str.c_str() );
stoi( str );

Example 4: how to convert from string to int in c++

#include <iostream>
#include <sstream>

using namespace std;

int main() {
    string s = "999";

    stringstream degree(s);

    int x = 0;
    degree >> x;

    cout << "Value of x: " << x;
}