What is function call in C

 A function call in C is a way to invoke a function to execute its code from another part of the program.

 It consists of the function name followed by parentheses (), optionally containing parameters.

 A function call can be divided into two main parts: function definition and function calling.

Types of Functions Call in C 

1Built-in Functions:

 Provided by the C standard library, such as printf(), scanf().

 Built-in functions in C are predefined functions provided by the C standard library to perform common tasks like input/output operations, mathematical calculations, string manipulation, and memory management.

These functions offer a standardized and efficient way to execute operations without writing the code from scratch, enhancing code readability and reducing development time.

Example:

#include<stdio.h> 
#include<math.h>

int main() {
    double base = 2.0, exponent = 3.0, result;

    // Using pow() function to calculate power
    result = pow(base, exponent);

    printf("Result: %.2lf\n", result);

    return 0;
}
	

Output:

Result: 8.00

 In this example, the pow() function from the C standard library is used to calculate the power of a number.

 The base is raised to the exponent, and the result is printed as 8.00.

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2User-defined Functions:

 Defined by the programmer to perform specific tasks, enhancing code modularity and reusability.

 User-defined functions in C are functions that are created and defined by the programmer to perform specific tasks as per the program's requirements.

 These functions encapsulate a block of code into a reusable unit, enhancing code modularity, reusability, and maintainability.

 User-defined functions allow the programmer to break down complex tasks into smaller, manageable parts, making the code easier to understand and debug.

Function Declaration 

 A function declaration in C provides the compiler with information about the function's name, return type, and parameters, without specifying the actual function body.

 It serves as a prototype or blueprint for the function, allowing the compiler to understand the function's interface and validate its usage throughout the program.

Functions definition 

 function declaration in C is a statement that informs the compiler about the function's name, return type, and parameters, without providing the actual function body.

 It serves as a blueprint or prototype for the function, allowing the compiler to recognize the function and validate its usage before the function is defined or called in the program.

Syntax:

return_type function_name(parameter_type1 parameter_name1, parameter_type2 parameter_name2, ...);

 return_type: Specifies the data type of the value returned by the function. It can be void if the function does not return any value.

 function_name: Name of the function that uniquely identifies i

 parameter_type1, parameter_type2, ...: Data types of the function parameters. If the function has no parameters, the parentheses () are left empty.

 parameter_name1, parameter_name2, ...: Names of the function parameters.

Function Calling 

 Function calling in C refers to the process of invoking or executing a function to perform its defined task.

 To call a function, you use the function's name followed by parentheses.

Example:

// Program for Function call in C
#include<stdio.h>

// Function Declaration
void greet();

int main() {
    // Function Call
    greet();

    return 0;
}

// Function Definition
void greet() {
    printf("Hello, World!\n");
}

Output:

Hello, World!

In this Example:

Function Declaration:

void greet(); declares a function named greet that takes no parameters and returns void (no return value).

Function Call:

greet(); calls the greet function from within the main() function.

Function Definition:

The greet function definition defines the behavior of the function, which in this case, prints "Hello, World!" to the console.