C# 当我在eg'*'；如果出现错误，请随意编辑代码

操作错误单击两个操作时，我希望进行错误处理，因此我无法将多个*放在一行中

namespace Calculator_Assignment
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        float num, ans;
        int count;
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private void Button_click(object sender, EventArgs e)
        {
            Button button = (Button)sender;          //adds the numbers into the screen when clicked
            Screen.Text = Screen.Text + button.Text;
            Screen.ForeColor = Color.Red; //text that entered appears red

        }

        private void operatorclick(object sender, EventArgs e)
        {
            Button button = (Button)sender;            //adds the symbols into the screen when clicked
            Screen.Text = Screen.Text + button.Text;  //all symbols are under button_click so i do not have to repeat the code over/
        }

        private void Clearclick(object sender, EventArgs e)
        {
            Screen.Clear(); //when clicked clears the screen
            Result.Clear(); //when clicked clears the result 

        }

        private void Decimalclick(object sender, EventArgs e)
        {
            Screen.Text = Screen.Text + "."; //adds decimal point to screen when/if clicked 
            Screen.ForeColor = Color.Red; //decimal point appears red


        }

        private void Closebtn_Click(object sender, EventArgs e)
        {
            this.Close(); // closes the application down 
        }

        private void plusclick(object sender, EventArgs e) //addition
        {

            num = float.Parse(Screen.Text);
            Screen.Clear(); //clears the screen of everything
            Screen.Focus(); //textbox is focused upon when the screen is cleared
            count = 1; //this counts the store case
            Screen.Text = num.ToString() + "+"; //this puts the text onto the top text box


        }

        private void multiplyclick(object sender, EventArgs e) //multiply 
        {
            num = float.Parse(Screen.Text);
            Screen.Clear(); //clears the screen of everything
            Screen.Focus(); //textbox is focused upon when the screen is cleared
            count = 3; //this counts the store case
            Result.Text = num.ToString() + "*"; //this puts the text onto the top textbox          
        }

        private void divideclick(object sender, EventArgs e)  //divide
        {
            num = float.Parse(Screen.Text);
            Screen.Clear(); //clears the screen of everything
            Screen.Focus(); //textbox is focused upon when the screen is cleared
            count = 4; //this counts the store case
           Screen.Text = num.ToString() + "/"; //this puts the text onto the 
        }

        private void subtractclick(object sender, EventArgs e) //subtract
        {
            num = float.Parse(Screen.Text);
            Screen.Clear(); //clears the screen of everything
            Screen.Focus(); //textbox is focused upon when the screen is cleared
            count = 2; //this counts the store case
           Result.Text = num.ToString() + "-"; //this puts the text onto the label
        }

        private void equalsclick(object sender, EventArgs e)
        {          
            switch (count) //initalising switch statement 
            {
                case 1:
                     ans = num + float.Parse(Screen.Text);//Adding numbers 
                    Result.Text = ans.ToString();         //this converts my answer from a float to a string
                    break;
                case 2:
                    ans = num - float.Parse(Screen.Text); //Subtracting numbers
                    Result.Text = ans.ToString();         //float to a string 
                    break;
                case 3:
                    ans = num * float.Parse(Screen.Text);  //Multiplying numbers
                    Result.Text = ans.ToString();          //float to a string 
                    break;
                case 4:
                    ans = num / float.Parse(Screen.Text); //Division of numbers
                    Result.Text = ans.ToString();         //float to a string
                    break;
                default:                                  //the default figure
                    break;         
            }






        }







        }
    }

快速解决方案：

创建一个名为

void AppendOperator（字符串运算符）

此方法应在追加前一个字符之前检查它。如果前一个字符是运算符，则只需返回

调用此新方法，以替换为

Result.Text赋值的所有位置

附加运算符实现示例：

    private readonly HashSet<char> _operators = new HashSet<char>() { '+', '*', '-', '/' };

    void AppendOperator(string operation)
    {
        char lastChar = Result.Text.LastOrDefault();
        if (_operators.Contains(lastChar)) return;

        Result.Text = num.ToString() + operation;
    }

private readonly HashSet_operators=new HashSet（）{'+'，'*'，'-'，'/'}；
无效附加运算符（字符串操作）
{
char lastChar=Result.Text.LastOrDefault（）；
if（_operators.Contains（lastChar））返回；
Result.Text=num.ToString（）+操作；
}
brilliant谢谢你，方法代码实际上是什么？一分钟（不是在笔记本电脑前）回答了你的问题吗？还有什么我可以帮忙的吗？