Simple Calculator using C#
Posted by Samath
Last Updated: December 30, 2020
  140413

This is a simple calculator written using the C# programming language. This calculator is similar to a small handheld calculator and has the standard four functions for addition, subtraction, division, and multiplication. You can use your numeric keypad to insert numbers along with the keys 'equals', 'backspace', 'delete', as well as the  + - * / keys. 

Code:

using System;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
        public partial class Form1 : Form
        {
                public Form1()
                {
                        InitializeComponent();
                }
                float num1, ans;
                int count;
 
                private void btnC_Click_1(object sender, EventArgs e)
                {
                        textBox1.Clear();
                        count = 0; 
                }
 
                private void btnCE_Click(object sender, EventArgs e)
                {
                        
                        if (num1==0 && textBox1.TextLength>0)
                        { 
                                num1 = 0; textBox1.Clear();  
                        }
                        else if (num1 > 0 && textBox1.TextLength > 0)
                        { 
                                textBox1.Clear();
                        }
                
                }
 
                private void btnback_Click(object sender, EventArgs e)
                {
                     
                        int lenght = textBox1.TextLength-1;
                        string text = textBox1.Text;  
                        textBox1.Clear();
                        for (int i = 0; i < lenght; i++)
                                textBox1.Text = textBox1.Text + text[i]; 
                
                }
 
                private void btnminus_Click(object sender, EventArgs e)
                {
                        if (textBox1.Text != "")
                        {
                                num1 = float.Parse(textBox1.Text);
                                textBox1.Clear();
                                textBox1.Focus();
                                count = 1;
                        }
                }
 
                private void btnone_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 1;
                }
 
                private void bttntwo_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 2;
                }
 
                private void btnthree_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 3;
                }
 
                private void btnplus_Click(object sender, EventArgs e)
                {
                        num1 = float.Parse(textBox1.Text);
                        textBox1.Clear();
                        textBox1.Focus();
                        count = 2;
                }
 
                private void btnfour_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 4;
                }
 
                private void btnfive_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 5;
                }
 
                private void btnsix_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 6;
                }
 
                private void btnmultiply_Click(object sender, EventArgs e)
                {
                        num1 = float.Parse(textBox1.Text);
                        textBox1.Clear();
                        textBox1.Focus();
                        count = 3;
                }
 
                private void btnseven_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 7;
                }
 
                private void btneight_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 8;
                }
 
                private void btnnine_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 9;
                }
 
                private void btndivide_Click(object sender, EventArgs e)
                {
                        num1 = float.Parse(textBox1.Text);
                        textBox1.Clear();
                        textBox1.Focus();
                        count = 4; 
                }
 
                private void btnzero_Click(object sender, EventArgs e)
                {
                        textBox1.Text = textBox1.Text + 0;
                }
 
                private void btnperiod_Click(object sender, EventArgs e)
                {
                        int c = textBox1.TextLength;
                        int flag = 0;
                        string text = textBox1.Text;
                        for (int i = 0; i < c; i++)
                        { 
                                if (text[i].ToString() == ".") 
                                { 
                                        flag = 1; break; 
                                } 
                                else 
                                { 
                                        flag = 0; 
                                } 
                        }
                        if (flag == 0)
                        { 
                                textBox1.Text = textBox1.Text + "."; 
                        }
                }
 
                private void btnequal_Click(object sender, EventArgs e)
                {
                        compute(count);
                }
 
                public void compute(int count)
                {
                        switch (count)
                        {
                                case 1:
                                        ans = num1 - float.Parse(textBox1.Text);
                                        textBox1.Text = ans.ToString();
                                        break;
                                case 2:
                                        ans = num1 + float.Parse(textBox1.Text);
                                        textBox1.Text = ans.ToString();
                                        break;
                                case 3:
                                        ans = num1 * float.Parse(textBox1.Text);
                                        textBox1.Text = ans.ToString();
                                        break;
                                case 4:
                                        ans = num1 / float.Parse(textBox1.Text);
                                        textBox1.Text = ans.ToString();
                                        break;
                                default:
                                        break;
                        }
                }
             
         }
}

 

   
  
 
 
   

 
 
The power of Events and OOP, simply beautiful T_T
 
true!
 
Here is the link to download theĀ source codeĀ for this file. Enjoy!
https://docs.google.com/open?id=0B4PXJilumj_INktzaHlFUUx5LTA
 
This code seem interesting & a little complex, but it's great. I can't wait 2  start once more again in di world of programming. The key of computing is within our hands, the future generation of programming... di code above sell off...
 
respect mi boss.
 
highly rated bro..!!! 
 
Thanks
 
very creative...
 
great!
 
thanks gan.
 
Thanks for this Tutorial.
 
Sir can i ask a question about visual c#?? how to solve an age in c#??
 
I need it because its my assignment can you answer it??? plz
 
Why when i click the button like 1,2,3 it wont appear on the textbox? Anyone help me please. Thanks