C#初级——方法/函数(ref 和 out关键字)（引用传参和输出传参）
ref关键字
ref是引用的方式传递参数，参数必须初始化。也就意味传入方法中的不再是形参，而是引用该实参。ref关键字在定义 和 使用时需要在前面添加 ref关键字表示引用，对比代码如下：
ref引用传参
//ref:引用的方式传递参数public static int findMax(ref int num1, ref int num2)//public static int findMax(int num1, int num2){num1 *= 2;num2 *= 2;return num1 + num2;}private static void Main(string[] args){//参数必须初始化不然会报错int num1 = 1;int num2 = 2;int num3 = 0;num3 = findMax(ref num1, ref num2);//num3 = findMax(num1, num2);Console.WriteLine($"num1 = {num1}, num2 = {num2}, num3 = {num3}");//num1 = 2, num2 = 4, num3 = 6Console.ReadKey();}值传参
//ref:引用的方式传递参数//public static int findMax(ref int num1, ref int num2)public static int findMax(int num1, int num2){num1 *= 2;num2 *= 2;return num1 + num2;}private static void Main(string[] args){//参数必须初始化不然会报错int num1 = 1;int num2 = 2;int num3 = 0;//num3 = findMax(num1, num2);num3 = findMax(num1, num2);Console.WriteLine($"num1 = {num1}, num2 = {num2}, num3 = {num3}");//num1 = 1, num2 = 2, num3 = 6Console.ReadKey();}out关键字
out关键字与ref关键字一样也是引用传递，在使用out修饰的参数，在定义的时候，可以初始化，也可以不初始化，但是，在方法内部必须赋值。
out输出传参
public static int result(int num1, int num2, out int num3)//public static int result(int num1, int num2, int num3){num3 = (num1 + num2) / 2;return num3;}private static void Main(string[] args){int num1 = 2;int num2 = 4;int num3 = 0;int avg = 0;avg = result(num1, num2, out num3);//avg = result(num1, num2, num3);Console.WriteLine($"avg = {avg}, num3 = {num3}"); //avg = 3, num3 = 3Console.ReadKey();}值传递
//public static int result(int num1, int num2, out int num3)public static int result(int num1, int num2, int num3){num3 = (num1 + num2) / 2;return num3;}private static void Main(string[] args){int num1 = 2;int num2 = 4;int num3 = 0;int avg = 0;//avg = result(num1, num2, out num3);avg = result(num1, num2, num3);Console.WriteLine($"avg = {avg}, num3 = {num3}"); //avg = 3, num3 = 0Console.ReadKey();}