Library function in C

Library functions in C offer pre-written code that can be utilized to perform various tasks efficiently.

These functions are categorized into two types: standard library functions and user-defined functions.

Standard Library Functions

Standard library functions are provided by the C standard library and are available for use in any C program.

They cover a wide range of tasks, including input/output operations, string manipulation, mathematical computations, memory management, and more.

Examples include printf(), scanf(), strlen(), malloc(), strcpy(), etc.

Standard library functions simplify programming tasks by providing ready-made solutions for common operations.

---

User-Defined Functions:

User-defined functions are created by programmers to perform specific tasks within a program.

They encapsulate a set of instructions and can be called multiple times from different parts of the program.

User-defined functions enhance code readability, modularity, and reusability.

They allow programmers to break down complex tasks into smaller, more manageable units.

---

Advantages of Library Functions:

Efficiency: Library functions are optimized for performance and have been thoroughly tested for reliability, ensuring efficient execution of tasks.

Time-Saving: By utilizing pre-written functions, programmers can save time and effort, avoiding the need to reinvent the wheel for common tasks.

Portability: Standard library functions are part of the C standard, making them highly portable across different platforms and compilers.

Consistency: Standard library functions adhere to standardized specifications, promoting code consistency and interoperability.

---

Example:

Program 1: Using a Standard Library Function (printf())

// Program for Using a Standard Library Function (printf()) 
#include<stdio.h> 

int main() {
    int num = 10;
    
    // Using printf() to display the value of num
    printf("The value of num is: %d\n", num);
    
    return 0;
}

Output:

The value of num is: 10

Program 2: Creating a User-Defined Function

// Program for Creating a User-Defined Function
#include<stdio.h>

// Function to calculate the square of a number
int square(int x) {
    return x * x;
}

int main() {
    int num = 5;
    
    // Calling the user-defined function square() and printing the result
    printf("The square of %d is: %d\n", num, square(num));
    
    return 0;
}

Output:

The square of 5 is: 25