Actual and Formal Parameters in C

Last Updated on September 22, 2023 by Mayank Dham

Understanding the intricacies of programming languages involves delving into the fundamental concepts that govern their functionality. In the realm of C programming, the concepts of actual and formal parameters play a pivotal role in function calls. These parameters facilitate communication between different parts of a program and enable the seamless transfer of data. This article provides an insightful exploration of actual and formal parameters in C, shedding light on their significance, usage, and the underlying mechanics that make them essential tools for every programmer. Before moving to the difference between actual and formal arguments in C programming, let’s first discuss what are actual parameters in C programming.

What are Actual Parameters in C?

Actual parameters are the values that are passed to the function during a function call. They are also known as arguments. Actual parameters are used to provide the values to the formal parameters of the function. Actual parameters can be of any data type such as int, float, char, etc.

Syntax of Actual Parameters in C

function_name(actual_parameter1, actual_parameter2, ...);

Example of Actual Parameters in C

int main()
{
    int sum= add(10, 20);
    return 0;
}

What are Formal Parameters in C?

Formal parameters are also called function parameters or function arguments. They are used in the function definition to accept the values from the caller of the function. Formal parameters are declared in the function definition and are used to represent the data that will be passed to the function at the time of the function call. Formal parameters can be of any data type such as int, float, char, etc.

Syntax of Formal Parameters in C

return_type function_name(parameter1_type parameter1_name, parameter2_type parameter2_name, ... )
{
    // function body
}

Example of Formal Parameters in C

int add(int a, int b)
{
    return a + b;
}

Example of Actual and Formal Parameters in C

#include<stdio.h>
int add(int a, int b){
    int sum = a + b;
    return sum;
}
int main()
{
    int sum = add(10, 20);
    return 0;
}

Explanation of Actual and Formal Parameters in C
In the actual and formal parameters example, a and b are formal parameters or formal arguments. When this function is called with actual parameters, these parameters are passed to the function as arguments. Here, 10 and 20 are actual parameters that are passed to the add() function.

are actual parameters that are passed to the add() function.
We had discussed the examples for actual and formal parameters in C programming. Let’s see the difference between actual and formal arguments in C programming.

Difference Between Actual and Formal Parameters in C

Here, are some of the differences between actual and formal parameters in C:

Advantages of Actual and Formal Parameters in C

Here are some advantages of actual and formal parameters in C:

• Actual parameters allow passing values or variables to the function which is called.
• They create more flexible and reusable functions.
• These make code more readable and easier to maintain.
• Formal parameters specify the data type, ensuring correct data usage and preventing errors.
• Formal parameters define variables to receive values passed from the calling function.

Disadvantages of Actual and Formal Parameters in C

Here are some disadvantages of actual and formal parameters in C:

• Actual parameters can cause side effects if modified by called functions.
• Formal parameters can add overhead and complexity to function calls.
• Passing large data structures as parameters can be inefficient.
• Incorrect parameter usage can lead to difficult-to-debug errors.
• Changing parameter lists requires modifying all calling functions.

Conclusion
The synergy between actual and formal parameters in C programming forms the backbone of function calls. The ability to pass data and values between different parts of a program, while maintaining the integrity of the original data, is a cornerstone of efficient and modular coding. As you continue your journey as a C programmer, remember that mastering the art of handling actual and formal parameters empowers you to design elegant, modular, and highly functional programs that stand the test of time.

Frequently Asked Questions(Faqs):

1. What are the actual parameters in C?
Actual parameters, also known as arguments, are the values passed to a function during a function call. These values can be constants, variables, or expressions.

2. What are formal parameters in C?
Formal parameters, also known as parameters or function parameters, are the variables declared in the function definition that receive the values passed as arguments during a function call.

3. What is the difference between actual parameters and formal parameters in C?
The main difference between actual parameters and formal parameters is that actual parameters are the values passed to a function during a function call, whereas formal parameters are the variables declared in the function definition that receive these values.

4. How are actual parameters and formal parameters passed in C?
In C, actual parameters and formal parameters can be passed by value or by reference. By default, C uses pass-by-value, but pass-by-reference can be achieved by passing pointers to the arguments.

5. What is pass-by-value in C?
Pass-by value is a method of passing arguments to a function in which the value of the argument is copied into the formal parameter of the function. Any changes made to the formal parameter inside the function will not affect the original argument passed to the function.

6. What is pass by reference in C?
Pass by reference is a method of passing arguments to a function in which the address of the argument is passed to the formal parameter of the function. Any changes made to the formal parameter inside the function will affect the original argument passed to the function.