在没有 try-catch 块的情况下控制格式异常

问题描述

除了使用 #columns = ['a','b','c','d','e'] 语句之外，还有什么方法可以捕获格式异常吗？如果用户输入的内容超过单个字符，则会出现格式异常。这是我的代码：

try-catch

解决方法

与其依赖控制流的异常，您应该始终首先尝试避免它们。在您的情况下，您可以使用 Read 而不是 ReadLine 来实现。因此，您只能读取一个字符：

Console.WriteLine("Would you like to play RPS? y/n");
char playOrNot = Convert.ToChar(Console.Read());
while(!validateChoice(playOrNot))
{
    Console.WriteLine("Invalid! please re-enter selection");
    playOrNot = Convert.ToChar(Console.Read());
}

,

有多种选择。

1 改用字符串：

public void Menu()
{
    Console.WriteLine("Would you like to play RPS? y/n");
    string playOrNot = Console.ReadLine();
    while(!validateChoice(playOrNot))
    {
        Console.WriteLine("Invalid! please re-enter selection");
        playOrNot = Console.ReadLine();
    }
    if (playOrNot.ToUpper() == "Y")
    {
        Console.Clear();
        PlayGame();
    }
}
public bool validateChoice(string playornot)
{
    return !"YN".Contains(playOrNot);
}

2 使用 Console.ReadKey：

public void Menu()
{
    Console.WriteLine("Would you like to play RPS? y/n");
    char playOrNot = Console.ReadKey();
    while(!validateChoice(playOrNot))
    {
        Console.WriteLine("Invalid! please re-enter selection");
        playOrNot = Console.ReadKey();
    }
    if (char.ToUpper(playOrNot) == 'Y')
    {
        Console.Clear();
        PlayGame();
    }
}
public bool validateChoice(char playornot)
{
    return !"YN".Contains(char.ToUpper(playOrNot));
}

3 使用简单的方法从 ReadLine 中获取字符：

public void Menu()
{
    Console.WriteLine("Would you like to play RPS? y/n");
    char playOrNot = GetChar();
    while(!validateChoice(playOrNot))
    {
        Console.WriteLine("Invalid! please re-enter selection");
        playOrNot = Console.GetChar();
    }
    if (char.ToUpper(playOrNot) == 'Y')
    {
        Console.Clear();
        PlayGame();
    }
}
public bool validateChoice(char playornot)
{
    return !"YN".Contains(char.ToUpper(playOrNot));
}
public char GetChar()
{
    string line = Console.ReadLine();
    if (line.Length == 1)
        return line[0]; // first char of line
    return (char)0;
}