String to Integer in Different Programming Languages

Last Updated : 24 Aug, 2024

Below are example programs to do string to integer conversion in different programming languages.

C++

#include <bits/stdc++.h>
using namespace std;

int main()
{
    int val;
    char strn1[] = "12546";

    val = atoi(strn1);
    cout << "String value = " << strn1 << endl;
    cout << "Integer value = " << val << endl;

    char strn2[] = "GeeksforGeeks";
    val = atoi(strn2);
    cout << "String value = " << strn2 << endl;
    cout << "Integer value = " << val << endl;

    return (0);
}

// This code is contributed by shivanisinghss2110

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    int val;
    char strn1[] = "12546";

    val = atoi(strn1);
    printf("String value = %s\n", strn1);
    printf("Integer value = %d\n", val);

    char strn2[] = "GeeksforGeeks";
    val = atoi(strn2);
    printf("String value = %s\n", strn2);
    printf("Integer value = %d\n", val);

    return (0);
}

Java

import java.util.*;

public class Main {
    public static void main(String[] args)
    {
        int val;
        String strn1 = "12546";

        val = Integer.parseInt(strn1);
        System.out.println("String value = " + strn1);
        System.out.println("Integer value = " + val);

        String strn2 = "GeeksforGeeks";
        try {
            val = Integer.parseInt(strn2);
            System.out.println("String value = " + strn2);
            System.out.println("Integer value = " + val);
        }
        catch (NumberFormatException e) {
            val = 0;
            System.out.println("String value = " + strn2);
            System.out.println("Integer value = " + val);
        }
    }
}

Python

def main():
    strn1 = "12546"
    val = int(strn1)
    print("String value = ", strn1)
    print("Integer value = ", val)

    strn2 = "GeeksforGeeks"
    try:
        val = int(strn2)
    except ValueError:
        val = 0
        print("String value = ", strn2)
        print("Integer value = ", val)


if __name__ == "__main__":
    main()

using System;

namespace GeeksforGeeks {
class Program {
    static void Main(string[] args)
    {
        String strn1 = "12546";
        int val = int.Parse(strn1);
        Console.WriteLine("String value = " + strn1);
        Console.WriteLine("Integer value = " + val);

        String strn2 = "GeeksforGeeks";
        try {
            val = int.Parse(strn2);
        }
        catch (FormatException e) {
            val = 0;
            Console.WriteLine("String value = " + strn2);
            Console.WriteLine("Integer value = " + val);
        }
    }
}
}

JavaScript

// Javascript code to convert string to integer
let val;
let strn1 = "12546";

val = parseInt(strn1);
console.log("String value = " + strn1);
console.log("Integer value = " + val);

let strn2 = "GeeksforGeeks";
val = parseInt(strn2);
console.log("String value = " + strn2);
console.log("Integer value = " + val);

// This code is contributed by prasad264

Output

String value = 12546
Integer value = 12546
String value = GeeksforGeeks
Integer value = 0

Complexity Analysis of Standard Functions

Below is a typical time complexity analysis of the library functions

Time Complexity: O(n), Only one traversal of the string is needed.
Space Complexity: O(1), As no extra space is required.

Detailed Articles for Different Languages:

Below are detailed articles in different programming languages to do string to integer conversion.

String to Integer in C/C++
String to Integer in Java
String to Integer in JavaScript
String to Integer in Python
String to Integer in C#
String to Integer in PHP

How to implement your own conversion?

We need to write a function that takes a string as an argument and returns its equivalent integer value. Please refer the below post for details.

Write your own string to integer converter.

String to Integer in Different Programming Languages

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String to Integer in Different Programming Languages

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Detailed Articles for Different Languages:

How to implement your own conversion?

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