Concatenation of a Complicated String Causing Issues - winforms

Question

I have assigned a piece of code to a string in a proper format. Checked that it works fine. Now I wish to get a copy of this code concatenated to the old code on a button click.Also there are variables within the string which take up values from textboxes. But somehow these variables(arrays) are not able to store the last values. I want to generate the code while placing all the variables at proper places.
public string oldCode;
public int counter=0;
string[] AffUrl = new string[100];
string[] ImgUrl = new string[100];
private void button1_Click(object sender, EventArgs e)
{
AffUrl[counter] =textBox1.Text;
ImgUrl[counter] = textBox2.Text;
string code = #"<div style=""float:left;padding-right:30px;padding-bottom:30px;"">
<div>
<img src=""" + ImgUrl[counter] + #""" height=""200px"" width=""200px"" />
</div>
<div>
<button onclick=""myFunction()"">Try it</button>
<script type=""text/javascript"">
function myFunction" + counter + #"() {
var btn = document.createElement(""BUTTON"");
window.open(""" + AffUrl[counter] + #""", ""_self"")
}
</script>
</div>
</div>";
oldCode = code;
oldCode = string.Concat(code,oldCode);
counter++;
richTextBox1.Text =oldCode;
}

Answer 1

As written, you're always concatenating the new value to itself. Remove the oldCode = code assignment.

Answer 2

</div>";
oldCode = code; <= here you reset the cache - are you sure that's intended?
oldCode = string.Concat(code,oldCode);

Answer 3

Ok, I got it!
You can place a condition over "oldCode=code;
public string oldCode;
public int counter = 0;
string[] AffUrl = new string[100];
string[] ImgUrl = new string[100];
private void button1_Click(object sender, EventArgs e)
{
AffUrl[counter] = textBox1.Text;
ImgUrl[counter] = textBox2.Text;
string code = #"<div style=""float:left;padding-right:30px;padding-bottom:30px;"">
<div>
<img src=""" + ImgUrl[counter] + #""" height=""200px"" width=""200px"" />
</div>
<div>
<button onclick=""myFunction()"">Try it</button>
<script type=""text/javascript"">
function myFunction" + counter + #"() {
var btn = document.createElement(""BUTTON"");
window.open(""" + AffUrl[counter] + #""", ""_self"")
}
</script>
</div>
</div>";
if (counter == 0)
{
oldCode = code;
}
oldCode = string.Concat(code, oldCode);
counter++;
richTextBox1.Text = oldCode;
}
}
}