C# 判断语句详解与应用示例小结

if (条件)
{
    // 条件为真时执行的代码块
}

switch (表达式)
{
    case 值1:
        // 当表达式的值等于值1时执行的代码块
        break;
    case 值2:
        // 当表达式的值等于值2时执行的代码块
        break;
    // ...
    default:
        // 当表达式的值不匹配任何case时执行的代码块
        break;
}

条件 ? 表达式1 : 表达式2

int a = 5;
if (a > 0)
{
    Console.WriteLine("a大于0");
}

int number = 1;
switch (number)
{
    case 1:
        Console.WriteLine("number等于1");
        break;
    case 2:
        Console.WriteLine("number等于2");
        break;
    default:
        Console.WriteLine("number不等于1或2");
        break;
}

int max = (5 > 3) ? 5 : 3;
Console.WriteLine("max的值是：" + max);

string username = "admin";
string password = "123456";
if (username == "admin" && password == "123456")
{
    Console.WriteLine("登录成功");
}
else
{
    Console.WriteLine("登录失败");
}

int num = 10;
switch (num)
{
    case 1:
        Console.WriteLine("num等于1");
        break;
    case 2:
        Console.WriteLine("num等于2");
        break;
    default:
        Console.WriteLine("num不等于1或2");
        break;
}

Console.WriteLine("请输入操作：1. 添加 2. 删除 3. 修改");
string operation = Console.ReadLine();
switch (operation)
{
    case "1":
        Console.WriteLine("执行添加操作");
        break;
    case "2":
        Console.WriteLine("执行删除操作");
        break;
    case "3":
        Console.WriteLine("执行修改操作");
        break;
    default:
        Console.WriteLine("无效操作");
        break;
}