C# 交換兩個變量值

1. 聲明兩個變量：int n1 = 10, n2 = 20;要求將兩個變量交換，最后輸出n1為20,n2為10。擴展（*）：不使用第三個變量如何交換？

int n1 = 10;
int n2 = 20;
int temp;

temp = n1;
n1 = n2;
n2 = temp;

▲ 借用中間量

int n1 = 10;
int n2 = 20;


n1 = n1 + n2;
n2 = n1 - n2;
n1 = n1 - n2;

▲ 不用中間量

2. 用方法來實現：將上題封裝一個方法來做，方法有兩個參數分別為num1,num2,將num1與num2交換。提示：方法有兩個參數n1,n2,在方法中將n1與n2進行交換，使用ref。（*）

static void Main(string[] args)
{
    int n1 = 10;
    int n2 = 20;

    Console.WriteLine("交換前：n1 = {0}, n2 = {1}", n1, n2);


    SwapNum<int>(ref n1, ref n2);

    Console.WriteLine("交換前：n1 = {0}, n2 = {1}", n1, n2);
    Console.ReadKey();
}

static void SwapNum<T> (ref T a, ref T b)
{
    T temp;
    
    temp = a;
    a = b;
    b = temp;
}

運行結果：

交換前：n1 = 10, n2 = 20
交換前：n1 = 20, n2 = 10

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參考：

1.link-01