Question

This code changes the textbox instantly to red. I want it like, click button then red, again then green.

private void button1_Click(object sender, EventArgs e)
{

    textBox1.BackColor = System.Drawing.Color.Black;

    if (textBox1.BackColor.Equals(System.Drawing.Color.Black)) 
    {
        textBox1.BackColor = System.Drawing.Color.Red;
    }



    if (textBox1.BackColor.Equals(System.Drawing.Color.Red))
    {
        textBox1.BackColor = System.Drawing.Color.Green;
    }



    if (textBox1.BackColor.Equals(System.Drawing.Color.Green))
    {
        textBox1.BackColor = System.Drawing.Color.Blue;
    }



    if (textBox1.BackColor.Equals(System.Drawing.Color.Blue))
    {
        textBox1.BackColor = System.Drawing.Color.Red;
    }
}

Answer 1

You want to use an else if:

if (textBox1.BackColor.Equals(System.Drawing.Color.Black)) 
{
    textBox1.BackColor = System.Drawing.Color.Red;
} 
else if (textBox1.BackColor.Equals(System.Drawing.Color.Red))
{
    textBox1.BackColor = System.Drawing.Color.Green;
} 
else if (textBox1.BackColor.Equals(System.Drawing.Color.Green))
{
    textBox1.BackColor = System.Drawing.Color.Blue;
} 
else if (textBox1.BackColor.Equals(System.Drawing.Color.Blue))
{
    textBox1.BackColor = System.Drawing.Color.Red;
}

What you were doing is changing it to red, then checking if it is red and changing it to green. By using else if you won’t execute the if red if it is black.

Also, as Tim points out in the comments, you need to remove the line textBox1.BackColor = System.Drawing.Color.Black to stop if from been black on every click. Set it to black in your form’s constructor.