我执行此语句是为了检查TextBox是否为空,但无论TextBox是否为空,MessageBox都会显示出来。
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 < 50)
{
int index = dataGridView1.Rows.Add();
dataGridView1.Rows[1].Cells[4].Value = "F";
}
else if (MarkNumericUpDown.Value > 50 && MarkNumericUpDown.Value <= 64)
{
dataGridView1.Rows[index].Cells[4].Value = "F";
}*/
发布于 2011-05-28 02:49:31
请尝试此条件:
if (string.IsNullOrWhiteSpace(MaterialTextBox.Text)) {
// Message box
}
这将处理一些只包含空格字符的字符串,并且您不必处理字符串相等问题,这有时会很棘手
发布于 2011-05-28 03:12:49
那么,在检查文本框是否为空之前,您需要清除文本框
/* !! 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();
}
发布于 2011-05-28 02:47:52
使用如下内容:
if (String.IsNullOrEmpty(MaterialTextBox.Text))
https://stackoverflow.com/questions/6156458
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