实参和形参的区别

1. Overview

Many programmers use the terms argument and parameter interchangeably, although they have different meanings. Hence, we’ll look at the difference between an argument and a parameter in this tutorial.

2. Parameters  and Arguments

Let’s see a pseudocode example to show clear defenitions of the terms parameter and argument. In fact, a method or function in this program takes two numbers as inputs and outputs the sum of those values:

algorithm Sum(a, b):
    // INPUT
    //   a, b = Numbers to be added
    // OUTPUT
    //   Returns the sum of a and b

    Sum <- a + b
    return Sum

algorithm Main():
    // OUTPUT
    //   Prints the result of Sum

    a <- 5
    b <- 10
    result <- Sum(a, b)
    print result

2.1. Parameters

The parameters are the variables that we can define in the function declaration. In fact, we utilized these variables within the function. Also, the programming language in the function description determines the data type specification. These variables facilitate the function’s entire execution. In addition, they are known as local variables because they are only available within the function.

Now, let’s understand these variables in detail with the help of the example above. The function ab contains two values inside the parenthesis, , and . So, and  are the parameters. In fact, these are two local variables, with a lifetime limited to the function. They can also take any values that are given to the function when it is called.

2.2. Arguments

The arguments are the variables given to the function for execution. Besides, the local variables of the function take the values of the arguments and therefore can process these parameters for the final output.

Now, let’s look at the function calling in the pseudocode above. So, at the end of the pseudocode, we invoked the function . In other words, the arguments are the real values that we give as input to get the desired output. So, in our example, we choose and as arguments, then the obtained output will be .

3. The Difference Between an Argument and a Parameter

When building functions, we can make certain inputs in order to process the instructions included in the function. In this context, we frequently use the terms “arguments” and “parameters” interchangeably to refer to these inputs. To clarify, we take a look at the differences to see which to use in which situation. Let’s now summarize the main differences between arguments and parameters:

We used the variables in the function to send the value of the calling function to the receiving function.

We defined the parameters when defining the function.

We used the arguments to transfer values from the calling function to the receiving function in function call statements.

To get the value from the arguments, we utilized the local variables in the function declaration.

We always assigned each argument to the parameter in the function declaration at the moment of the call.

When we invoked the function, the values of the arguments are assigned to the local variables.

Actual Parameters is another name for them.

They’re sometimes referred to as Formal Parameters.

4. Conclusion

In this tutorial, we discussed the main difference between arguments and parameters. We demonstrated when and how they are used.