c# textbox not displaying all contents

Question

I want to have a textbox that displays the word Seq (which is a column name), then lists values from mylist underneath it. So far, the values from the list show up but the word Seq doesn't

  private void button7_Click(object sender, EventArgs e)
          {
              if (seq1) 
              {
                  textBox1.Text = " Seq"; // This guy doesn't showup in the textbox
                  foreach (object o in SeqIrregularities)
                  {
                      textBox1.Text = String.Join(Environment.NewLine, SeqIrregularities);
                  }
              }

          }

Answer 1

You're reassigning the value of textBox1.Text to your list of values, rather than appending the list of values to the textbox contents.

Try this:

 textBox1.Text = " Seq"; // This guy doesn't showup in the textbox
 textBox1.Text += Environment.NewLine + String.Join(Environment.NewLine, SeqIrregularities);

You also don't need to loop through your irregularities if what you're doing is creating a concatenated string of them.

Another way to do it (which may be clearer):

string irregularities = String.Join(Environment.NewLine, SeqIrregularities);
string displayString = " Seq" + Environment.NewLine + irregularities;
textBox1.Text = displayString;

Answer 2

change your code to this:

  private void button7_Click(object sender, EventArgs e)
          {
              if (seq1) 
              {
                  textBox1.Text = " Seq"; // This guy doesn't showup in the textbox
                  foreach (object o in SeqIrregularities)
                  {
                      textBox1.Text += String.Join(Environment.NewLine, SeqIrregularities);
                  }
              }

          }

You were overwriting your text in each iteration of your foreach-statement. You have to use += instead of = in your foreach-statement.