Converting Strings to Numbers in C/C++

In this tutorial, we will be discussing a program to understand how to convert strings into numbers in C/C++.

C/C++ provides two ways to convert strings into numbers.

Example

 Live Demo

Using sscanf()

#include<stdio.h>
int main(){
   const char *str = "12345";
   int x;
   sscanf(str, "%d", &x);
   printf("\nThe value of x : %d", x);
   return 0;
}

Output

The value of x : 12345

Using stoi()

 Live Demo

#include <iostream>
#include <string>
using namespace std;
int main(){
   string str1 = "45";
   string str2 = "3.14159";
   string str3 = "31337 geek";
   int myint1 = stoi(str1);
   int myint2 = stoi(str2);
   int myint3 = stoi(str3);
   cout << "stoi(\"" << str1 << "\") is " << myint1 << '\n';
   cout << "stoi(\"" << str2 << "\") is "<< myint2 << '\n';
   cout << "stoi(\"" << str3 << "\") is "<< myint3 << '\n';
   return 0;
}

Output

stoi("45") is 45
stoi("3.14159") is 3
stoi("31337 geek") is 31337

Ayush Gupta

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Updated on: 16-Mar-2020

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