The use of three parameters of ref, out, and Params in Unity3D

ref

作用：
将一个变量传入一个函数中进行"处理","处理"完成后,再将"处理"后的值带出函数.
语法：
Both formal and actual parameters must be added when usedref关键字.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test: MonoBehaviour {
    
	void Start () {
    
        int a = 1;
        int b = 2;
        refTest(ref a, b);
        Debug.Log("a:" + a + " " + "b:" + b);
	}
    private void refTest(ref int num1,int num2)
    {
    
        num1 = 5;
        num2 = 10;

    }
	void Update () {
    
		
	}
}

输出：

out

作用：
一个函数中如果返回多个不同类型的值,就需要用到out参数.
语法：
It is not necessary to assign values ​​to variables outside the function,But inside the function must assign a value to the function.And both formal parameters and actual parameters should be addedout关键字.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test : MonoBehaviour
{
    
    void Start()
    {
    
        int b;
        outTest(out b);
        Debug.Log("b:" + b);
    }
    private void outTest(out int num1)
    {
    
        num1 = 5;

    }
    void Update()
    {
    
        
    }
}

输出：

注意：
outThe real assignment of the modified parameter is inside the function,Assignment outside is useless,具体如下：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Test : MonoBehaviour
{
    
    void Start()
    {
    
        int b;
        b = 10;
        outTest(out b);
        Debug.Log("b:" + b);
    }
    private void outTest(out int num1)
    {
    
        num1 = 5;

    }
    void Update()
    {
    
        
    }
}

输出

Params

可变参数params(数组参数)Allows us to dynamically pass in a different number of parameters.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Test : MonoBehaviour
{
    
    public void Getdd(params int[] pp)
    {
    
        foreach (var p in pp)
        {
    
            print(p);
        }
    }
    void Start()
    {
    
        Getdd(1, 2, 3);
    }
    void Update()
    {
    
    }
}

输出：