I have a question about my code for a calculator

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Hello codeproject

My problem is that i currently making a calculator in c#, and this is some of the problems i have:

It crashes when i divide by 0.

When i wanna make it show the whole calculation, it will reverse the signs used
(plus = minus, minus = plus and so on)

How can i solve them??
I hope you will understand my problem, and try help me.
Sorry if my english is bad.
PS some of it is in Danish so just ignore the comments after //
Thanks for the help

C#


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Calculator{
    public partial class CalForm : Form {
        bool plus = false;
        bool minus = false;
        bool multiply = false;
        bool divide = false;
        bool equal = false;
        public CalForm() {
            InitializeComponent();
            Text = "Calculator";
        }

        private void CalForm_Load(object sender, EventArgs e) {
        }
        // 1
        private void button1_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "1";
        }
        // 2
        private void button2_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "2";
        }
        // 3
        private void button3_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "3";
        }
        // 4
        private void button4_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "4";
        }
        // 5
        private void button5_Click(object sender, EventArgs e) {
            if (equal)
            {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "5";
        }
        // 6
        private void button6_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "6";
        }
        // 7
        private void button7_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "7";
        }
        // 8
        private void button8_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "8";
        }
        // 9
        private void button9_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "9";
        }
        // 0
        private void button14_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "0";
        }
        // ,
        private void button15_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            if (textBox1.Text.Contains(",")) {
                return;
            }
            else {
                textBox1.Text = textBox1.Text + ",";
            }
        }
        //Dette er plus
        private void button11_Click(object sender, EventArgs e) {
            if (textBox1.Text == "") {
                return;
            }
            else {
                plus = true;
                textBox1.Tag = textBox1.Text;
                textBox1.Text = "+";
            }
        }
        //Dette er "lig med" for regne reglerne i lommeregneren
        private void button13_Click(object sender, EventArgs e) {
            equal = true;
            if (plus) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) + Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (minus) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) - Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (multiply) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) * Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (divide) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) / Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
        }
        //Dette er minus
        private void button12_Click(object sender, EventArgs e) {
            if (textBox1.Text == "") {
                return;
            }
            else {
                minus = true;
                textBox1.Tag = textBox1.Text;
                textBox1.Text = "-";
        }
    }
        //Dette er gange
        private void button16_Click(object sender, EventArgs e) {
            if (textBox1.Text == "") {
                return;
            }
            else {
                multiply = true;
                textBox1.Tag = textBox1.Text;
                textBox1.Text = "";
            }
        }
        //Dette er clear
        private void button17_Click(object sender, EventArgs e) {
            plus = minus = multiply = divide = false;
            textBox1.Tag = textBox1.Text;
            textBox1.Text = "";
        }
        // Dette er divider
        private void button10_Click(object sender, EventArgs e) {
            if (textBox1.Text == "") {
                return;
            }
            else {
                divide = true;
                textBox1.Tag = textBox1.Text;
                textBox1.Text = "";
            }
        }
        //Dette er pi
        private void button19_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "3,14";
        }
        //Dette er tau
        private void button21_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "6,28";
        }
        //Dette er e
        private void button20_Click(object sender, EventArgs e) {
            if (equal) {
                textBox1.Text = "";
                equal = false;
            }
            textBox1.Text = textBox1.Text + "2,71";
            // Dette er så man ikke kan dividere med 0
            
            }
        }
    }
}

Posted 10-Nov-12 9:03am

Member 9589245

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2 solutions

Solution 3

just put that on try catch block

Posted 10-Nov-12 16:36pm

mohitjain1943

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Pepin z Hane · Accepted Answer · 2012-11-10T10:08:00

divide by zero:

C#

private void button13_Click(object sender, EventArgs e) {
            equal = true;
            if (plus) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) + Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (minus) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) - Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (multiply) {
                decimal deo = Convert.ToDecimal(textBox1.Tag) * Convert.ToDecimal(textBox1.Text);
                textBox1.Text = deo.ToString();
            }
            if (divide) {
                try
                {
                    decimal deo = Convert.ToDecimal(textBox1.Tag) / Convert.ToDecimal(textBox1.Text);
                    textBox1.Text = deo.ToString();
                }
                catch (DivideByZeroException)
                {
                  MessageBox.Show ("Cannot Divide by zero!")
                }
            }
        }

and the second problem is much more complicated... You have operators type boolean, so when you declare Plus_Click, Minus_Click and so on, you have to set the others to false.

Example:

C#

//Dette er plus
        private void button11_Click(object sender, EventArgs e) {
            if (textBox1.Text == "") {
                return;
            }
            else {
                plus = true;
                minus = false;
                multiply = false;
                divide = false;
                equal = false;
                textBox1.Tag = textBox1.Text;
                textBox1.Text = "+";
            }
        }

In this code I can't see any more errors, maybe it could be in different class.

I hope this helps.

-Pepin z Hane