The Enter Key doesn't trigger anything in my form or control

Question

I have a calculator app in windows form that work very well when I use mouse for doing operation. I added some code and make it to work with keyboard and keypad. All things work well except ENTER Key. When I do an operation and press the ENTER key, it doesn't trigger anything, but the equal key work fine.
I search a lot and used keypress and keydown events, but it doesn't work and my Enter key doesn't stimulate the equal sign.
the complete code is as follow:

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 frmCalculator : Form
    {
        double x, y, z;
        string op;
        Boolean flag;

        public frmCalculator()
        {
            InitializeComponent();
        }

        private void btnEqual_Click(object sender, EventArgs e)
        {
            y = Convert.ToDouble(txtDisplay.Text);
            switch(op)
            {
                case "+":
                    z = x + y;
                    break;
                case "-":
                    z = x - y;
                    break;
                case "*":
                    z = x * y;
                    break;
                case "/":
                    z = x / y;
                    break;
            }
            txtDisplay.Text = z.ToString();
            op = null;

        }

        private void txtDisplay_TextChanged(object sender, EventArgs e)
        {
            btnPoint.Enabled = !txtDisplay.Text.Contains(".");
            btnBackSpace.Enabled = Convert.ToBoolean(txtDisplay.Text.Length);

        }

        private void btnBackSpace_Click(object sender, EventArgs e)
        {
            if (txtDisplay.TextLength>0)
            txtDisplay.Text = txtDisplay.Text.Substring(0, txtDisplay.Text.Length - 1);
        }

        private void frmCalculator_Load(object sender, EventArgs e)
        {
            txtDisplay_TextChanged(null, null);
        }

        private void frmCalculator_KeyPress(object sender, KeyPressEventArgs e)
        {
            foreach (Button x in panelNumbers.Controls)
                if (x.Text == e.KeyChar.ToString())
                {
                    x.Focus();
                    x.ForeColor = Color.Red;
                }
                else
                    x.ForeColor = Color.Black;


            Button temp = new Button();
           temp.Text = e.KeyChar.ToString();
            if (e.KeyChar >= '0' && e.KeyChar <= '9')
                Numbers(temp, null);
            else if (e.KeyChar == '+' || e.KeyChar == '-' || e.KeyChar == '*' || e.KeyChar == '/')
                Operators(temp, null);
            else if (e.KeyChar == '=')
                btnEqual_Click(null, null);
            else if (e.KeyChar == '.' && txtDisplay.Text.Contains(".") == false)
                Numbers(temp, null);
            else if (e.KeyChar == '\b')
                btnBackSpace_Click(null, null);

        }

        private void frmCalculator_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyData == Keys.Enter)
                btnEqual_Click(null, null);
        }


        private void Operators(object sender, EventArgs e)
        {
            if (op != null)
                btnEqual_Click(null, null);
            x = Convert.ToDouble(txtDisplay.Text);
            op = ((Button)sender).Text;
            flag = true;
        }



        private void Numbers(object sender, EventArgs e)
        {

            if (flag==true)
            {
                txtDisplay.Text = "";
                flag = false;
            }
            txtDisplay.Text += ((Button)sender).Text;
        }
    }
}

Answer 1

Is it possible that you did not bind the frmCalculator_KeyDown event to the form, causing the following codes to fail to execute:

         private void frmCalculator_KeyDown(object sender, KeyEventArgs e)  
         {  
             if (e.KeyData == Keys.Enter)  
                 btnEqual_Click(null, null);  
         }  

Try adding a breakpoint in the method to check it.

In addition, why not move the code in this method to the frmCalculator_KeyPress method?

Since you said that all the other keys are useful, there must be no problem with this method.

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Answer 2

Inside of the form load event try adding this statement:

This.KeyPreview = True: