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C# | Design a simple calculator using if else if statements

C# if else if example: Here, we are going to design a simple calculator using if else if conditional statements in C#.
Submitted by Pankaj Singh, on December 25, 2018 [Last updated : March 18, 2023]

Calculator using if else if Statements

The task is to design a simple calculator using if else if statements with following operations:

1. Addition
2. Subtraction
3. Multiplication
4. And, division

C# program to design calculator using if else if statements

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DecisionMaking2 {
  class Program {
    static void Main(string[] args) {
      Console.WriteLine("Calculator");
      Console.WriteLine("----------------------------");
      Console.WriteLine("1.Add");
      Console.WriteLine("2.Substract");
      Console.WriteLine("3.Multiply");
      Console.WriteLine("4.Divide");
      
      Console.Write("Enter Choice(1-4):");
      int ch = Int32.Parse(Console.ReadLine());
      
      int a, b, c;
      
      if (ch == 1) {
        Console.Write("Enter A:");
        a = Convert.ToInt32(Console.ReadLine());
        Console.Write("Enter B:");
        b = Convert.ToInt32(Console.ReadLine());
        c = a + b;
        Console.WriteLine("Sum = {0}", c);
      } else if (ch == 2) {
        Console.Write("Enter A:");
        a = Convert.ToInt32(Console.ReadLine());
        Console.Write("Enter B:");
        b = Convert.ToInt32(Console.ReadLine());
        c = a - b;
        Console.WriteLine("Difference = {0}", c);
      } else if (ch == 3) {
        Console.Write("Enter A:");
        a = Convert.ToInt32(Console.ReadLine());
        Console.Write("Enter B:");
        b = Convert.ToInt32(Console.ReadLine());
        c = a * b;
        Console.WriteLine("Product = {0}", c);
      } else if (ch == 4) {
        Console.Write("Enter A:");
        a = Convert.ToInt32(Console.ReadLine());
        Console.Write("Enter B:");
        b = Convert.ToInt32(Console.ReadLine());
        c = a / b;
        Console.WriteLine("Quotient = {0}", c);
      } else {
        Console.WriteLine("Invalid Choice");
      }
      
      Console.ReadKey();
    }
  }
}

Output

First run:

Calculator
----------------------------
1.Add
2.Substract
3.Multiply
4.Divide
Enter Choice(1-4):1
Enter A:10
Enter B:20
Sum = 30


Second run:

Calculator
----------------------------
1.Add
2.Substract
3.Multiply
4.Divide
Enter Choice(1-4):4
Enter A:10
Enter B:20
Quotient = 0


Third run:

Calculator
----------------------------
1.Add
2.Substract
3.Multiply
4.Divide
Enter Choice(1-4):5
Invalid Choice

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