# Difference Between Actual and Formal Parameters

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The difference Between Actual and Formal Parameters is that the actual parameter is used to invoke or pass the information while executing the program. In contrast, formal parameters are declared while calling the function. Actual and Formal Parameters are an important part of a program.

It is always important to define the purpose of the parameter in a program. Let us know more about the difference between actual and formal parameters in the coming sections, along with knowing what is actual and formal parameters.

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Table of content

## Difference Between Actual and Formal Parameters

The major difference between actual and formal parameters is that formal parameters are defined when the function is called, whereas actual parameters are defined when the function is invoked.

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### Key Differences Between Actual and Formal Parameters

 Actual Parameters Formal Parameters Defined when it is invoked. Defined when the function is called. Passed on calling a function They will be in the called function. Data types will not be mentioned. The data type must be included. They are written in the function call. They are written in the function definition. They may be constant values. They can be local variables.

## Actual and Formal Parameters

The parameters are used to either pass or send out the information in a program. It is an essential part of any programming language to use the function.

### Difference between Actual and Formal Parameters PDF

They are used to perform a specific task. There are two types of parameters that are widely used:

• Actual Parameters
• Formal Parameters

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### What are the Actual Parameters?

An actual parameter is the value of a function that is passed when the function is being invoked. The caller will assign the actual value. It is a parameter that is determined while inviting a subroutine.

Example of Actual Parameters

#include

void multiplication (int x, int y) {

int multiplication;

addition = x*y;

printf(“%d”,multiplication);

}

void main () {

multiplication (2,3);

multiplication (4,5);

}

### What are the Formal Parameters?

Let us learn about the formal parameters. A formal parameter is defined while determining the subroutine. Formal parameters are also used in the header of the function.

The syntax of the formal parameters is:

(formal parameters) {

//set of statements to be executed

}

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