运算符’*’不能应用于’string’和’int’类型的操作数

namespace exer4 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void btnTotal_Click(object sender, EventArgs e) { int overtime = Convert.ToInt32(txtHours.Text) - 30; int salary = Convert.ToInt32(txtHours.Text)*250; double tax = (salary + overtime) * .10; int deduction = salary - (300 + 400); //operator '>' cannot be applied to operands of type 'string' and 'int' if Convert.ToInt32(txtHours.Text > 30) { lblName.Text = txtName.Text; lblSalary.Text = Convert.ToString(overtime *120) + (salary - (deduction - tax)); } else { // //operator '*' cannot be applied to operands of type 'string' and 'int' lblSalary.Text = Convert.ToString(txtHours.Text) * 250; } } } 

Answer 1

你的if语句应该是

 if (Convert.ToInt32(txtHours.Text) > 30) 

而另一条线应该是

 lblSalary.Text = Convert.ToString(Convert.ToInt32(txtHours.Text) * 250); 

或者更好的是将txtHours文本转换为int并将其保存在变量中以便重用。

  private void btnTotal_Click(object sender, EventArgs e) { int hours = Convert.ToInt32(txtHours.Text); int overtime = hours - 30; int salary = hours * 250 double tax = (salary + overtime) * .10; int deduction = salary - (300 + 400); if(hours > 30) { lblName.Text = txtName.Text; lblSalary.Text = ((overtime *120) + (salary - (deduction - tax))).ToString(); } else { lblSalary.Text = salary.ToString(); } } 

Answer 2

你想做：

 if (Convert.ToInt32(txtHours.Text) > 30) { //normal code here } else { //normal code } 

如果首先需要像你一样将它解析为int，那么进行比较，以便if可以测试布尔条件。

Answer 3

尝试

 if (Convert.ToInt32(txtHours.Text) > 30) { ...