Basic calculator

[sanddy1911]

I'm new to c# and try to make a Basic calculator this is how far I came

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

namespace Calculator
{
    public partial class Calculator : Form
    {
        private int firstValue =0;
        private int secondValue =0;
        private char opration = '0';
        
        public Calculator()
        {
            InitializeComponent();            
        }

        private void Calculator_Load(object sender, EventArgs e)
        {
            //txtDisplay.Text = "0";
        }

        private void btn1_Click(object sender, EventArgs e)
        {
           txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "1");
        }

        private void btn2_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "2");
        }

        private void btn3_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "3");
        }

        private void btn4_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "4");
        }

        private void btn5_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "5");
        }

        private void btn6_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "6");
        }

        private void btn7_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "7");
        }

        private void btn8_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "8");
        }

        private void btn9_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = txtDisplay.Text.Insert(txtDisplay.TextLength, "9");
        }

        private void btnPlus_Click(object sender, EventArgs e)
        {
                firstValue =+ Convert.ToInt32(txtDisplay.Text);
                opration = '+';
                txtDisplay.Text = "";
        }

        private void btnMinus_Click(object sender, EventArgs e)
        {
                firstValue =- Convert.ToInt32(txtDisplay.Text);
                opration = '-';
                txtDisplay.Text = "";
        }

        private void btnMulti_Click(object sender, EventArgs e)
        {
                firstValue *= Convert.ToInt32(txtDisplay.Text);
                opration = '*';
                txtDisplay.Text = "";
        }

        private void btnDiv_Click(object sender, EventArgs e)
        {
                firstValue /= Convert.ToInt32(txtDisplay.Text);
                opration = '/';
                txtDisplay.Text = "";
        }

        private void btnCLear_Click(object sender, EventArgs e)
        {
            txtDisplay.Text = "";
            firstValue = 0;
            secondValue = 0;
            opration = '0';
        }

        private void btnEqual_Click(object sender, EventArgs e)
        {
            
                switch (opration)
                {
                    case '+':
                        firstValue += Convert.ToInt32(txtDisplay.Text);
                        txtDisplay.Text = firstValue.ToString();
                        break;
                    case '-':
                        firstValue -= Convert.ToInt32(txtDisplay.Text);
                        txtDisplay.Text = firstValue.ToString();
                        break;
                    case '*':
                        firstValue *= Convert.ToInt32(txtDisplay.Text);
                        txtDisplay.Text = firstValue.ToString();
                        break;
                    case '/':
                        firstValue /= Convert.ToInt32(txtDisplay.Text);
                        txtDisplay.Text = firstValue.ToString();
                        break;
                    default:
                        break;
                }
           
        }
    }
}

i'm getting unexpected results can anyone help me.

 

[jmcilhinney]

There's a fair bit of code there. What results are you expecting, what results are you getting and where in the code, or at least where in the application, does this unexpected behaviour arise? Have you actually debugged that section of code, i.e. with breakpoints and stepping through the code?