string k = "kelimeklkkkk";
for (int i = 0; i < k.Length; i++)
{
int c = 0;
for (int j = 0; j < k.Length; j++)
{
if (k[i].Equals(k[j]))
{
c++;
}
}
if (!richTextBox1.Text.Contains(k[i] + " = " + c.ToString()))
richTextBox1.Text += k[i] + " = " + c.ToString() + Environment.NewLine;