Check if TextBox is empty and return MessageBox

Question

I made this statement to check if TextBox is empty  but the MessageBox always shows up  wether the TextBox is empty or not       private void NextButton Click object sender  EventArgs e                decimal MarkPoints  x  y          x   HoursNumericUpDown Value          y   MarkNumericUpDown Value          MarkPoints   x   y             decimal MarkPoints    decimal HoursNumericUpDown Value    decimal HoursNumericUpDown Value            DataGridViewRow dgvRow   new DataGridViewRow            DataGridViewTextBoxCell dgvCell    new DataGridViewTextBoxCell             dgvCell   new DataGridViewTextBoxCell            dgvCell Value   MaterialTextBox Text          dgvRow Cells Add dgvCell            dgvCell   new DataGridViewTextBoxCell            dgvCell Value   HoursNumericUpDown Value          dgvRow Cells Add dgvCell            dgvCell   new DataGridViewTextBoxCell            dgvCell Value   MarkNumericUpDown Value          dgvRow Cells Add dgvCell            dgvCell   new DataGridViewTextBoxCell            dgvCell Value   MarkPoints          dgvRow Cells Add dgvCell            dataGridView1 Rows Add dgvRow            MaterialTextBox Clear            HoursNumericUpDown Value   HoursNumericUpDown Minimum          MarkNumericUpDown Value   MarkNumericUpDown Minimum           if  String IsNullOrEmpty MaterialTextBox Text                         MessageBox Show  Enter Material Name Please     Error   MessageBoxButtons OK  MessageBoxIcon Warning                 dataGridView1 Rows Clear                      else                         if  MarkNumericUpDown Value  lt  50                                int index   dataGridView1 Rows Add                    dataGridView1 Rows 1  Cells 4  Value    F                             else if  MarkNumericUpDown Value  gt  50  amp  amp  MarkNumericUpDown Value  lt   64                                dataGridView1 Rows index  Cells 4  Value    F

User · Answer

Try this condition instead   if  string IsNullOrWhiteSpace MaterialTextBox Text            Message box     This will take care of some strings that only contain whitespace characters and you won t have to deal with string equality which can sometimes be tricky

User · Answer

Becasue is a TextBox already initialized would be better to control if there is something in there outside the empty string  which is no null or empty string I am afraid   What I did is just check is there is something different than  quot  quot   if so do the thing   if  TextBox Text     quot  quot     Something different than  quot  quot                           Do your stuff            else                         Do NOT do your stuff

User · Answer

Use something such as the following   if  String IsNullOrEmpty MaterialTextBox Text

User · Answer

Well  you are clearing the textbox right before you check if it s empty        This clears the textbox BEFORE you check if it s empty    MaterialTextBox Clear     HoursNumericUpDown Value   HoursNumericUpDown Minimum  MarkNumericUpDown Value   MarkNumericUpDown Minimum   if  String IsNullOrEmpty MaterialTextBox Text             MessageBox Show  Enter Material Name Please     Error   MessageBoxButtons OK     MessageBoxIcon Warning                 dataGridView1 Rows Clear

User · Answer

Try doing the following  if  String IsNullOrEmpty MaterialTextBox Text     String IsNullOrWhiteSpace MaterialTextBox Text                   do job           else               MessageBox Show  Please enter correct path            Hope it helps

User · Answer

Adding on to what  tjg184 said  you could do something like     if  String IsNullOrEmpty MaterialTextBox Text Trim

User · Answer

if  MaterialTextBox Text length  0    message

User · Answer

For multiple text boxes - add them into a list and show all errors into 1 messagebox      Append errors into 1 Message Box         List lt string gt  errors   new List lt string gt          if  string IsNullOrEmpty textBox1 Text                 errors Add  User               if  string IsNullOrEmpty textBox2 Text                 errors Add  Document Ref Code               if  errors Count  gt  0                errors Insert 0   The following fields are empty             string message   string Join Environment NewLine  errors           MessageBox Show message   errors   MessageBoxButtons OK  MessageBoxIcon Warning           return

[c#] Check if TextBox is empty and return MessageBox?

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