c# - 如何在 c# 中设置 windows 窗体以接受文本框和组合框中的空值
问题描述
我的 windows 窗体 c# 中有六行但有时我想隐藏几行,我知道如何将文本框或组合框的可见性设置为 false,但是当代码执行时,我得到“”输入字符串格式不正确""在下面提到的一行中出现错误,我如何将它们设置为接受空值?请帮助我已经被困了好几天了。
gpa.semester = comboBox1.SelectedItem.ToString();
gpa.subject = textBox1.Text;
gpa.credithours = Convert.ToInt32(comboBox2.Text);
gpa.marks = Convert.ToInt32(textBox2.Text);
private void button8_Click(object sender, EventArgs e) { gpaform4 gpa = new gpaform4();
gpa.semester = comboBox1.SelectedItem.ToString();
gpa.subject = textBox1.Text;
gpa.credithours = Convert.ToInt32(comboBox2.Text);
gpa.marks = Convert.ToInt32(textBox2.Text);
//gpa.semester1 = comboBox1.SelectedItem.ToString();
gpa.subject1 = textBox3.Text;
gpa.credithours1 = Convert.ToInt32(comboBox3.Text);
gpa.marks1 = Convert.ToInt32(textBox8.Text);
//gpa.semester2 = comboBox1.SelectedItem.ToString();
gpa.subject2 = textBox4.Text;
gpa.credithours2 = Convert.ToInt32(comboBox4.Text);
gpa.marks2 = Convert.ToInt32(textBox9.Text);
//gpa.semester3 = comboBox1.SelectedItem.ToString();
gpa.subject3 = textBox5.Text;
gpa.credithours3 = Convert.ToInt32(comboBox5.Text);
gpa.marks3 = Convert.ToInt32(textBox10.Text);
//gpa.semester4 = comboBox1.SelectedItem.ToString();
gpa.subject4 = textBox6.Text;
gpa.credithours4 = Convert.ToInt32(comboBox6.Text);
gpa.marks4 = Convert.ToInt32(textBox11.Text);
//gpa.semester5 = comboBox1.SelectedItem.ToString();
gpa.subject5 = textBox7.Text;
gpa.credithours5 = Convert.ToInt32(comboBox7.Text);
gpa.marks5 = Convert.ToInt32(textBox12.Text);
BLL tbll = new BLL();
bool b = tbll.Gpafrom4Bll(gpa);
if (b)
{
MessageBox.Show("GPA Calculated");
}
else
{
MessageBox.Show("GPA not Calculated");
}
Row1();
Row2();
Row3();
Row4();
Row5();
Row6();
textBox13.Text = total_credithours.ToString();
textBox14.Text = totalgragepoints.ToString();
textBox15.Text = ((totalgragepoints / total_credithours).ToString());
gpa sgpa = new gpa();
sgpa.semester = comboBox1.Text;
double testgpa = totalgragepoints / total_credithours;
sgpa.semestergpa = testgpa.ToString();
BLL tbll1 = new BLL();
tbll1.SgpaBll(sgpa);
}
解决方案
您可以在尝试使用该值之前检查 TextBox 值是 null 还是空 (String.IsNullOrEmpty),或者Int32.TryParse
改为使用该值。
如果你选择使用Convert.ToInt32
你应该使用异常处理(try-catch)。
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