What's the difference between an argument and a parameter?

A parameter is a variable in a method definition. When a method is called, the arguments are the data you pass into the method's parameters.

public void MyMethod(string myParam) { }

...

string myArg1 = "this is my argument";
myClass.MyMethod(myArg1);

Parameter is the variable in the declaration of the function.

Argument is the actual value of this variable that gets passed to the function.

Parameter is variable in the declaration of function.

Argument is the actual value of this variable that gets passed to function.

There is already a Wikipedia entry on the subject (see Parameter) that defines and distinguishes the terms parameter and argument. In short, a parameter is part of the function/procedure/method signature and an argument is the actual value supplied at run-time and/or call-site for the parameter.

The Wikipedia article also states that the two terms are often used synonymously (especially when reasoning about code informally):

Although parameters are also commonly referred to as arguments, arguments are more properly thought of as the actual values or references assigned to the parameter variables when the subroutine is called at runtime.

Given the following example function in C that adds two integers, x and y would be referred to as its parameters:

int add(int x, int y) {
    return x + y;
}

At a call-site using add, such as the example shown below, 123 and 456 would be referred to as the arguments of the call.

int result = add(123, 456);

Also, some language specifications (or formal documentation) choose to use parameter or argument exclusively and use adjectives like formal and actual instead to disambiguate between the two cases. For example, C/C++ documentation often refers to function parameters as formal arguments and function call arguments as actual arguments. For an example, see “Formal and Actual Arguments” in the Visual C++ Language Reference.

A parameter is something you have to fill in when you call a function. What you put in it is the argument.

Simply set: the argument goes into the parameter, an argument is the value of the parameter.

A bit more info on: http://en.wikipedia.org/wiki/Parameter_(computer_science)#Parameters_and_arguments

Always Remember that:
Arguments are passed while parameters are received.

Generally speaking, the terms parameter and argument are used interchangeably to mean information that is passed into a function.

Yet, from a function's perspective:

• A parameter is the variable listed inside the parentheses in the function definition.
• An argument is the value that is sent to the function when it is called.

The parameters of a function/method describe to you the values that it uses to calculate its result.

The arguments of a function are the values assigned to these parameters during a particular call of the function/method.

The terms are somewhat interchangeable. The distinction described in other answers is more properly expressed with the terms formal parameter for the name used inside the body of the function and parameter for the value supplied at the call site (formal argument and argument are also common).

Also note that, in mathematics, the term argument is far more common and parameter usually means something quite different (though the parameter in a parametric equation is essentially the argument to two or more functions).

Parameter is a variable in a function definition
Argument is a value of parameter

<?php

    /* define function */
    function myFunction($parameter1, $parameter2)
    {
        echo "This is value of paramater 1: {$parameter1} <br />";
        echo "This is value of paramater 2: {$parameter2} <br />";
    }

    /* call function with arguments*/
    myFunction(1, 2);

?>

I'm still not happy with all these answers. They all start talking about 'function declarations' and my monkey brain has already wandered off and started thinking about unicorns. That doesn't help me remember at all, it's just the definition.

I want something that I can immediately and forever hold in my head.

The only answer here that is of any use is:

"Arguments are actual values that are passed in".

Arguments are easier to define and as long as you know what they are then you know parameters are the other.

The other way I can think of it is:

• Arguments are the variables outside the function
• Parameters are the variables inside the function

Simplified down to:

Arguments outside, parameters inside

If any one wants to disagree with me, you can leave your arguments outside and bring your parameters in ;)

According to Joseph's Alabahari book "C# in a Nutshell" (C# 7.0, p. 49) :

static void Foo (int x)
{
    x = x + 1; // When you're talking in context of this method x is parameter
    Console.WriteLine (x);
}
static void Main()
{
    Foo (8); // an argument of 8. 
             // When you're talking from the outer scope point of view
}

In some human languages (afaik Italian, Russian) synonyms are widely used for these terms.

• parameter = formal parameter
• argument = actual parameter

In my university professors use both kind of names.

As my background and main environment is C, I will provide some statements/citations to that topic from the actual C standard and an important reference book, from also one of the developers of C, which is often cited and common treated as the first unofficial standard of C:

The C Programming Language (2nd Edition) by Brian W. Kernighan and Dennis M. Ritchie (April 1988):

Page 25, Section 1.7 - Functions

We will generally use parameter for a variable named in the parenthesized list in a function definition, and argument for the value used in the call of the function. The terms formal argument and actual argument are sometimes used for the same distinction.

ISO/IEC 9899:2018 (C18):

3.3

argument

actual argument

DEPRECATED: actual parameter

expression in the comma-separated list bounded by the parentheses in a function call expression, or a sequence of preprocessing tokens in the comma-separated list bounded by the parentheses in a function-like macro invocation.

3.16

parameter

formal parameter

DEPRECATED: formal argument

object declared as part of a function declaration or definition that acquires a value on entry to the function, or an identifier from the comma-separated list bounded by the parentheses immediately following the macro name in a function-like macro definition.

You need to get back to basics.Both constructors and methods have parameters and arguments.Many people even call constructors special kind of methods.This is how a method is declared parameters are used:

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

And this is how a constructor is declared parameters are used:

classname(parameters){
//body
}

Now lets see an example code using which we calculate the volume of a cube:

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);

           }
    }

So now you understand that when we call a constructor/method on an object at some place later in the code we pass arguments and not parameters.Hence parameters are limited to the place where the logical object is defined but arguments come into play when a physical object gets actually created.

• Parameter:
  • A value that is already "built in" to a function.
  • Parameters can be changed so that the function can be used for other things.
• Argument:
  • An input to a function
  • A variable that affects a functions result.

Source

This is a key:value issue...

The parameter is the key

The argument is the value

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

Example:

name: "Peter"

/********/

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

printName("Peter")

/********/

In this case, the parameter is "name", the argument is "Peter"

Consider the below java code.

public class Test{
   public String hello(String name){
      return "Hello Mr."+name;
   }

  public static void main(String args[]){
     Test test = new Test();
     String myName = "James Bond";
     test.hello(myName);
  }
}

The method definition of hello(String name) declares a String parameter called name. In the main method we are calling the hello method by passing the argument myName.

So parameter is the placeholder where as argument is the actual value for a method.