这是一个关键:价值问题……

参数是键

参数是值

/****************************************/

例子:

名称:“彼得”

/********/

let printName = (name) => console.log(name)

printName(“Peter”)

/********/

在本例中，参数是"name"，参数是"Peter"

函数的形式形参在函数声明中列出，并在函数定义的主体中使用。形式形参(任何类型的)是一种空白或占位符，在调用函数时用一些东西填充。

实参是用来填充形式形参的。当你写下一个函数调用时，实参会在函数名后面的括号中列出。在执行函数调用时，将插入形式形参的实参。

The terms call-by-value and call-by-reference refer to the mechanism that is used in the plugging-in process. In the call-by-value method only the value of the argument is used. In this call-by-value mechanism, the formal parameter is a local variable that is initialized to the value of the corresponding argument. In the call-by-reference mechanism the argument is a variable and the entire variable is used. In the call- by-reference mechanism the argument variable is substituted for the formal parameter so that any change that is made to the formal parameter is actually made to the argument variable.

参数和参数

All the different terms that have to do with parameters and arguments can be confusing. However, if you keep a few simple points in mind, you will be able to easily handle these terms. The formal parameters for a function are listed in the function declaration and are used in the body of the function definition. A formal parameter (of any sort) is a kind of blank or placeholder that is filled in with something when the function is called. An argument is something that is used to fill in a formal parameter. When you write down a function call, the arguments are listed in parentheses after the function name. When the function call is executed, the arguments are plugged in for the formal parameters. The terms call-by-value and call-by-reference refer to the mechanism that is used in the plugging-in process. In the call-by-value method only the value of the argument is used. In this call-by-value mechanism, the formal parameter is a local variable that is initialized to the value of the corresponding argument. In the call-by-reference mechanism the argument is a variable and the entire variable is used. In the call- by-reference mechanism the argument variable is substituted for the formal parameter so that any change that is made to the formal parameter is actually made to the argument variable.

来源:绝对的c++， Walter Savitch

也就是说,

这些术语在某种程度上是可以互换的。其他答案中描述的区别用术语形式形参表示函数体中使用的名称，用术语形参表示调用站点提供的值(形式实参和实参也很常见)更为恰当。

还要注意的是，在数学中，参数(argument)这个词更常见，而参数(parameter)通常意味着完全不同的东西(尽管参数方程中的参数本质上是两个或多个函数的参数)。

你得回到最基本的问题上来。构造函数和方法都有形参和实参。很多人甚至把构造函数称为特殊的方法。这是一个方法声明参数的使用方式:

      type name(parameters){
           //body of method
          }

这是构造函数声明参数的使用方式:

classname(parameters){
//body
}

现在让我们看一个计算立方体体积的示例代码:

public class cuboid {
    double width;
    double height;
    double depth;

      cuboid(double w,double h,double d) { 
      //Here w,h and d are parameters of constructor
       this.width=w;
       this.height=h;
       this.depth=d;
       }

        public double volume() {
        double v;
        v=width*height*depth;
        return v;
        }
        public static void main(String args[]){
           cuboid c1=new cuboid(10,20,30);
           //Here 10,20 and 30 are arguments of a constructor
           double vol;
           vol=c1.volume();
           System.out.println("Volume is:"+vol);

           }
    }

现在你明白了，当我们在代码后面的某个地方调用对象的构造函数/方法时，传递的是参数而不是形参。因此，形参仅限于定义逻辑对象的地方，而实参则在实际创建物理对象时发挥作用。

永远记住: 接收参数时传递参数。