拿if语句做一个分支，示例

static void Main(string[] args)

{

//提示并输入两个double值

string s;

WriteLine("输入一个数字");

double var1 = ToDouble(ReadLine());

WriteLine("输入另一个数字");

double var2 = ToDouble(ReadLine());

//根据var1和var2的值，给出字符串s赋值

if (var1 < var2)

s = "小鱼";

else

{

if (var1 == var2)

s = "等于";

else

s = "大于";

}

WriteLine($"var1{s}var2");

//按下任意键结束

ReadKey();

}