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Program to convert string to integer

Converting a string to an integer means converting a string that contains a numeric value into an integer data type. For example, converting the string "12345" to the integer 12345.

Here given code implementation process.

/*
    C program for
    Program to convert string to integer
*/
// Include header file
#include <stdio.h>
#include <stdlib.h> // for atoi
#include <string.h> // strlen

void stringToInteger(char num[])
{
	// Get length of num
	int n = strlen(num);
	printf("\n Given number : %s", num);
	// Case A
	// Use atoi function
	printf("\n Using atoi   : %d", atoi(num));
	// Case B
	// Custom code
	int result = 0;
	int i = 0;
	if (num[0] == '-')
	{
		// When num is negative number
		i = 1;
	}
	// This loop execute i..n
	// And combine digits to make integer
	while (i < n)
	{
		result = (result *10) + (num[i] - '0');
		i++;
	}
	if (num[0] == '-')
	{
		// When num is negative number
		result = -result;
	}
	printf("\n Result    : %d\n", result);
}
int main()
{
	// Given string numbers
	char num1[] = "12345";
	char num2[] = "-12345";
	char num3[] = "8000";
  	// Test Case
	stringToInteger(num1);
	stringToInteger(num2);
	stringToInteger(num3);
	return 0;
}

Output

 Given number : 12345
 Using atoi   : 12345
 Result    : 12345

 Given number : -12345
 Using atoi   : -12345
 Result    : -12345

 Given number : 8000
 Using atoi   : 8000
 Result    : 8000
/*
    Java Program for
    Program to convert string to integer
*/
public class Conversion
{
	public void stringToInteger(String num)
	{
		// Get length of given number
		int n = num.length();
		System.out.print("\n Given number : " + num);
		// Case A
		// Use parseInt function
		// Assume that given number is valid number
		int result1 = Integer.parseInt(num);
		// Display result1
		System.out.print("\n Using parseInt : " + result1);
		// Case B
		// Use valueOf function
		// Assume that given number is valid number
		int result3 = Integer.valueOf(num);
		// Display result3
		System.out.print("\n Using valueOf : " + result3);
		// Case C
		// Custom code
		int result2 = 0;
		int i = 0;
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + (num.charAt(i) - '0');
			i++;
		}
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		System.out.println("\n Result : " + result2);
	}
	public static void main(String[] args)
	{
		Conversion task = new Conversion();
		// Given string numbers
		String num1 = "12345";
		String num2 = "-12345";
		String num3 = "8000";
		// Test Case
		task.stringToInteger(num1);
		task.stringToInteger(num2);
		task.stringToInteger(num3);
	}
}

Output

 Given number : 12345
 Using parseInt : 12345
 Using valueOf : 12345
 Result : 12345

 Given number : -12345
 Using parseInt : -12345
 Using valueOf : -12345
 Result : -12345

 Given number : 8000
 Using parseInt : 8000
 Using valueOf : 8000
 Result : 8000
// Include header file
#include <iostream>

#include <string>

using namespace std;
/*
    C++ Program for
    Program to convert string to integer
*/
class Conversion
{
	public: void stringToInteger(string num)
	{
		// Get length of given number
		int n = num.length();
		cout << "\n Given number : " << num;
		// Case A
		// Use stoi function
		// Assume that given number is valid number
		int result1 = stoi(num);
		// Display result3
		cout << "\n Using stoi : " << result1;
		// Case C
		// Custom code
		int result2 = 0;
		int i = 0;
		if (num[0] == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 *10) + (num[i] - '0');
			i++;
		}
		if (num[0] == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		cout << "\n Result : " << result2 << endl;
	}
};
int main()
{
	Conversion *task = new Conversion();
	// Given string numbers
	string num1 = "12345";
	string num2 = "-12345";
	string num3 = "8000";
	// Test Case
	task->stringToInteger(num1);
	task->stringToInteger(num2);
	task->stringToInteger(num3);
	return 0;
}

Output

 Given number : 12345
 Using stoi : 12345
 Result : 12345

 Given number : -12345
 Using stoi : -12345
 Result : -12345

 Given number : 8000
 Using stoi : 8000
 Result : 8000
package main
import "strconv"
import "fmt"
/*
    Go Program for
    Program to convert string to integer
*/

func stringToInteger(num string) {
	// Get length of given number
	var n int = len(num)
	fmt.Print("\n Given number : ", num)
	// Case A
	// Use strconv.Atoi function
	// Assume that given number is valid number
	var result1 , err = strconv.Atoi(num)

	if err != nil {
		return
	}
	// Display result1
	fmt.Print("\n Using strconv.Atoi : ", result1)

	// Case B
	// Custom code
	var result2 int = 0
	var i int = 0
	if num[0] == '-' {
		// When num is negative number
		i = 1
	}
	// This loop execute i..n
	// And combine digits to make integer
	for (i < n) {
		result2 = (result2 * 10) + int(num[i] - '0')
		i++
	}
	if num[0] == '-' {
		// When num is negative number
		result2 = -result2
	}
	// Display result2
	fmt.Println("\n Result : ", result2)
}
func main() {
	
	// Given string numbers
	var num1 string = "12345"
	var num2 string = "-12345"
	var num3 string = "8000"
	// Test Case
	stringToInteger(num1)
	stringToInteger(num2)
	stringToInteger(num3)
}

Output

 Given number : 12345
 Using strconv.Atoi : 12345
 Result :  12345

 Given number : -12345
 Using strconv.Atoi : -12345
 Result :  -12345

 Given number : 8000
 Using strconv.Atoi : 8000
 Result :  8000

// Include namespace system
using System;
/*
    Csharp Program for
    Program to convert string to integer
*/
public class Conversion
{
	public void stringToInteger(String num)
	{
		// Get length of given number
		int n = num.Length;
		Console.Write("\n Given number : " + num);
		// Case A
		// Use Int32.Parse function
		// Assume that given number is valid number
		int result1 = Int32.Parse(num);
		// Display result1
		Console.Write("\n Using Int32.Parse : " + result1);
		// Case B
		// Use TryParse function
		// Assume that given number is valid number
      	int result3 = 0;
		Int32.TryParse(num,out result3);
		// Display result3
		Console.Write("\n Using TryParse : " + result3);
		// Case C
		// Custom code
		int result2 = 0;
		int i = 0;
		if (num[0] == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + (num[i] - '0');
			i++;
		}
		if (num[0] == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		Console.WriteLine("\n Result : " + result2);
	}
	public static void Main(String[] args)
	{
		Conversion task = new Conversion();
		// Given string numbers
		String num1 = "12345";
		String num2 = "-12345";
		String num3 = "8000";
		// Test Case
		task.stringToInteger(num1);
		task.stringToInteger(num2);
		task.stringToInteger(num3);
	}
}

Output

 Given number : 12345
 Using Int32.Parse : 12345
 Using TryParse : 12345
 Result : 12345

 Given number : -12345
 Using Int32.Parse : -12345
 Using TryParse : -12345
 Result : -12345

 Given number : 8000
 Using Int32.Parse : 8000
 Using TryParse : 8000
 Result : 8000
<?php
/*
    Php Program for
    Program to convert string to integer
*/
class Conversion
{
	public	function stringToInteger($num)
	{
		// Get length of given number
		$n = strlen($num);
		echo("\n Given number : ".$num);
		// Case A
		// Use number_format function
		// Assume that given number is valid number
		$result1 = number_format($num);
		// Display result1
		echo("\n Using number_format : ".$result1);
		// Case B
		// Custom code
		$result2 = 0;
		$i = 0;
		if ($num[0] == '-')
		{
			// When num is negative number
			$i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while ($i < $n)
		{
			$result2 = ($result2 * 10) + (ord($num[$i]) - ord('0'));
			$i++;
		}
		if ($num[0] == '-')
		{
			// When num is negative number
			$result2 = -$result2;
		}
		// Display result2
		echo("\n Result : ".$result2."\n");
	}
}

function main()
{
	$task = new Conversion();
	// Given string numbers
	$num1 = "12345";
	$num2 = "-12345";
	$num3 = "8000";
	// Test Case
	$task->stringToInteger($num1);
	$task->stringToInteger($num2);
	$task->stringToInteger($num3);
}
main();

Output

 Given number : 12345
 Using number_format : 12,345
 Result : 12345

 Given number : -12345
 Using number_format : -12,345
 Result : -12345

 Given number : 8000
 Using number_format : 8,000
 Result : 8000
/*
    Node JS Program for
    Program to convert string to integer
*/
class Conversion
{
	stringToInteger(num)
	{
		// Get length of given number
		var n = num.length;
		process.stdout.write("\n Given number : " + num);
		// Case A
		// Use parseInt function
		// Assume that given number is valid number
		var result1 = parseInt(num);
		// Display result1
		process.stdout.write("\n Using parseInt : " + result1);
		// Case B
		// Use Number function
		// Assume that given number is valid number
		var result3 = Number(num);
		// Display result3
		process.stdout.write("\n Using Number : " + result3);
		// Case C
		// Custom code
		var result2 = 0;
		var i = 0;
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + 
              (num.charAt(i).charCodeAt(0) - '0'.charCodeAt(0));
			i++;
		}
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		console.log("\n Result : " + result2);
	}
}

function main()
{
	var task = new Conversion();
	// Given string numbers
	var num1 = "12345";
	var num2 = "-12345";
	var num3 = "8000";
	// Test Case
	task.stringToInteger(num1);
	task.stringToInteger(num2);
	task.stringToInteger(num3);
}
main();

Output

 Given number : 12345
 Using parseInt : 12345
 Using Number : 12345
 Result : 12345

 Given number : -12345
 Using parseInt : -12345
 Using Number : -12345
 Result : -12345

 Given number : 8000
 Using parseInt : 8000
 Using Number : 8000
 Result : 8000
#    Python 3 Program for
#    Program to convert string to integer
class Conversion :
	def stringToInteger(self, num) :
		#  Get length of given number
		n = len(num)
		print("\n Given number : ", num, end = "")
		#  Case A
		#  Use int function
		#  Assume that given number is valid number
		result1 = int(num)
		#  Display result3
		print("\n Using int : ", result1, end = "")
		#  Case B
		#  Custom code
		result2 = 0
		i = 0
		if (num[0] == '-') :
			#  When num is negative number
			i = 1
		
		#  This loop execute i..n
		#  And combine digits to make integer
		while (i < n) :
			result2 = (result2 * 10) + (ord(num[i]) - ord('0'))
			i += 1
		
		if (num[0] == '-') :
			#  When num is negative number
			result2 = -result2
		
		#  Display result2
		print("\n Result : ", result2)
	

def main() :
	task = Conversion()
	#  Given string numbers
	num1 = "12345"
	num2 = "-12345"
	num3 = "8000"
	#  Test Case
	task.stringToInteger(num1)
	task.stringToInteger(num2)
	task.stringToInteger(num3)

if __name__ == "__main__": main()

Output

 Given number :  12345
 Using int :  12345
 Result :  12345

 Given number :  -12345
 Using int :  -12345
 Result :  -12345

 Given number :  8000
 Using int :  8000
 Result :  8000
#    Ruby Program for
#    Program to convert string to integer
class Conversion 
	def stringToInteger(num) 
		#  Get length of given number
		n = num.length
		print("\n Given number : ", num)
		#  Case A
		#  Use Integer function
		#  Assume that given number is valid number
		result1 = Integer(num)
		#  Display result1
		print("\n Using Integer : ", result1)
		#  Case B
		#  Use to_i 
		result3 = num.to_i
		#  Display result3
		print("\n Using to_i : ", result3)
		#  Case C
		#  Custom code
		result2 = 0
		i = 0
		if (num[0] == '-') 
			#  When num is negative number
			i = 1
		end

		#  This loop execute i..n
		#  And combine digits to make integer
		while (i < n) 
			result2 = (result2 * 10) + (num[i].ord - '0'.ord)
			i += 1
		end

		if (num[0] == '-') 
			#  When num is negative number
			result2 = -result2
		end

		#  Display result2
		print("\n Result : ", result2, "\n")
	end

end

def main() 
	task = Conversion.new()
	#  Given string numbers
	num1 = "12345"
	num2 = "-12345"
	num3 = "8000"
	#  Test Case
	task.stringToInteger(num1)
	task.stringToInteger(num2)
	task.stringToInteger(num3)
end

main()

Output

 Given number : 12345
 Using Integer : 12345
 Using to_i : 12345
 Result : 12345

 Given number : -12345
 Using Integer : -12345
 Using to_i : -12345
 Result : -12345

 Given number : 8000
 Using Integer : 8000
 Using to_i : 8000
 Result : 8000

/*
    Scala Program for
    Program to convert string to integer
*/
class Conversion()
{
	def stringToInteger(num: String): Unit = {
		// Get length of given number
		var n: Int = num.length();
		print("\n Given number : " + num);
		// Case A
		// Use parseInt function
		// Assume that given number is valid number
		var result1: Int = Integer.parseInt(num);
		// Display result1
		print("\n Using parseInt : " + result1);
		// Case B
		// Use valueOf function
		// Assume that given number is valid number
		var result3: Int = num.toInt;
		// Display result3
		print("\n Using valueOf : " + result3);
		// Case C
		// Custom code
		var result2: Int = 0;
		var i: Int = 0;
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + (num.charAt(i).toInt - '0'.toInt);
			i += 1;
		}
		if (num.charAt(0) == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		println("\n Result : " + result2);
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var task: Conversion = new Conversion();
		// Given string numbers
		var num1: String = "12345";
		var num2: String = "-12345";
		var num3: String = "8000";
		// Test Case
		task.stringToInteger(num1);
		task.stringToInteger(num2);
		task.stringToInteger(num3);
	}
}

Output

 Given number : 12345
 Using parseInt : 12345
 Using valueOf : 12345
 Result : 12345

 Given number : -12345
 Using parseInt : -12345
 Using valueOf : -12345
 Result : -12345

 Given number : 8000
 Using parseInt : 8000
 Using valueOf : 8000
 Result : 8000
/*
    Swift 4 Program for
    Program to convert string to integer
*/
class Conversion
{
	func stringToInteger(_ data: String)
	{	
      	let num = Array(data);
		// Get length of given number
		let n: Int = num.count;
		print("\n Given number : ", data, terminator: "");

		// Case A
		// Use valueOf function
		// Assume that given number is valid number
		let result1: Int = Int(data)!;
		// Display result1
		print("\n Using valueOf : ", result1, terminator: "");
		// Case B
		// Custom code
		var result2: Int = 0;
		var i: Int = 0;
		if (num[0] == "-")
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + 
              (Int(UnicodeScalar(String(num[i]))!.value) - 
               Int(UnicodeScalar(String("0"))!.value));
			i += 1;
		}
		if (num[0] == "-")
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		print("\n Result : ", result2);
	}
}
func main()
{
	let task: Conversion = Conversion();
	// Given string numbers
	let num1: String = "12345";
	let num2: String = "-12345";
	let num3: String = "8000";
	// Test Case
	task.stringToInteger(num1);
	task.stringToInteger(num2);
	task.stringToInteger(num3);
}
main();

Output

 Given number :  12345
 Using valueOf :  12345
 Result :  12345

 Given number :  -12345
 Using valueOf :  -12345
 Result :  -12345

 Given number :  8000
 Using valueOf :  8000
 Result :  8000
/*
    Kotlin Program for
    Program to convert string to integer
*/
class Conversion
{
	fun stringToInteger(num: String): Unit
	{
		// Get length of given number
		val n: Int = num.length;
		print("\n Given number : " + num);
		// Case A
		// Use toInt function
		// Assume that given number is valid number
		val result1: Int = num.toInt();
		// Display result1
		print("\n Using parseInt : " + result1);
		// Case B
		// Use toIntOrNull function
		// Assume that given number is valid number
		val result3 = num.toIntOrNull();
		// Display result3
		print("\n Using toIntOrNull : " + result3);
		// Case C
		// Custom code
		var result2: Int = 0;
		var i: Int = 0;
		if (num.get(0) == '-')
		{
			// When num is negative number
			i = 1;
		}
		// This loop execute i..n
		// And combine digits to make integer
		while (i < n)
		{
			result2 = (result2 * 10) + 
              (num.get(i).toInt() - '0'.toInt());
			i += 1;
		}
		if (num.get(0) == '-')
		{
			// When num is negative number
			result2 = -result2;
		}
		// Display result2
		println("\n Result : " + result2);
	}
}
fun main(args: Array < String > ): Unit
{
	val task: Conversion = Conversion();
	// Given string numbers
	val num1: String = "12345";
	val num2: String = "-12345";
	val num3: String = "8000";
	// Test Case
	task.stringToInteger(num1);
	task.stringToInteger(num2);
	task.stringToInteger(num3);
}

Output

 Given number : 12345
 Using parseInt : 12345
 Using toIntOrNull : 12345
 Result : 12345

 Given number : -12345
 Using parseInt : -12345
 Using toIntOrNull : -12345
 Result : -12345

 Given number : 8000
 Using parseInt : 8000
 Using toIntOrNull : 8000
 Result : 8000
Last updated on by Kalkicode




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