Function in C | About, Types and Examples
Have you heard of functions in the C programming language? Let's explore it, including its types and examples in detail!
A function in C is a collection of statements designed to execute a specific task when invoked. These self-contained units of code, often referred to as subroutines or procedures in other programming languages, play a pivotal role in structuring a C program. They provide a way to break down a program into smaller, manageable units, which makes the code more readable, reusable, and maintainable.
Read about User Defined Functions in C
Also, explore Function Prototype in C
Let’s see the types of Functions below:
Syntax of Function in C
return_type function_name(parameter_list) {
// body of the function
// ...
return return_value;
}
Let us understand each part of the syntax in detail
return_type: This specifies the type of data that the function will return. It can be any valid data type in C such as int, float, char, etc., or void if the function does not return any value.
function_name: This is the name of the function, which you use to call the function elsewhere in your program. It can be any valid identifier name in C.
parameter_list: This is a list of parameters that the function takes as input. Parameters are specified as a comma-separated list of type name pairs, such as int a, float b. If the function takes no parameters, you can use the keyword void or leave it empty.
The body of the function: This is a block of code enclosed in curly braces {}. This is where you write the code that implements the functionality of the function.
return: This keyword is used to return a value from the function. The type of the value being returned must match the return_type specified in the function definition. If the return_type is void, you can simply use the return; statement without any value, or omit the return statement entirely.
Example to understand the above part
#include <stdio.h>
// Function definitionint add_numbers(int a, int b) { // int is the return type, add_numbers is the function name, and it takes two parameters of type int int sum; // local variable to hold the sum of the two numbers sum = a + b; // calculating the sum of the two numbers return sum; // returning the sum}
int main() { int result = add_numbers(7, 3); // Calling the function with 5 and 3 as arguments printf("The result is: %d\n", result); // Printing the result return 0; // Returning 0 to indicate successful execution}
Output
The result is: 10
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Let’s Understand Functions by Relating them With a Real-Life Example
Read Later
Imagine a software product that manages a library’s book inventory. Here’s a small example demonstrating a function
#include <stdio.h>
typedef struct { char title[100]; char author[100]; int year_published;} Book;
void display_book_details(Book book) { printf("Title: %s\n", book.title); printf("Author: %s\n", book.author); printf("Year Published: %d\n", book.year_published);}
int main() { Book myBook = {"One Hundred Years of Solitude", "Gabriel García Márquez", 1967};
display_book_details(myBook);
return 0;}
Output
Title: One Hundred Years of Solitude Author: Gabriel García Márquez Year Published: 1967
In the above example:
- Function Definition: display_book_details is a function defined to display the details of a book.
- Return Type: The function has a void return type because it does not return any value; it only prints details.
- Function Name: display_book_details is the name of the function.
- Parameters: The function takes a Book structure as a parameter, which contains details about a book.
- Calling the Function: The function is called from the main function with myBook as the argument.
So, in this product, the display_book_details function can be seen as a tool that library staff use to quickly display details of a book in the inventory, helping them to manage and catalog books more efficiently.
Let’s Understand the Types of Functions in Detail:
1. Built-in Functions
Built-in functions in C, often referred to as library functions or standard library functions, are predefined functions that are part of the C standard library. These functions provide essential capabilities to C programmers and can be used without the need for writing their implementations.
Some types of Built-in Functions with examples
1. String Manipulation Functions (<string.h>)
These functions provide various ways to manipulate and work with strings.
- strcpy(): Copies one string into another.
- strlen(): Returns the length of a string.
- strcmp(): Compares two strings.
- strcat(): Concatenates two strings.
Example
#include <stdio.h>#include <string.h>
int main() { char source[] = "Hello, Learn C Programming with Shiksha Online!"; char destination[50];
strcpy(destination, source);
printf("Source String: %s\n", source); printf("Destination String: %s\n", destination);
return 0;}
Output
Source String: Hello, Learn C Programming with Shiksha Online! Destination String: Hello, Learn C Programming with Shiksha Online!
In this example, strcpy() is used to copy the content of source string into destination string. It illustrates the importance of being able to copy strings safely and easily in C programming.
2. Mathematical Functions (<math.h>)
These functions help you perform various mathematical operations.
- pow(): Returns the power of a number.
- sqrt(): Returns the square root of a number.
- sin(), cos(), tan(): Trigonometric functions.
- log(): Returns the natural logarithm of a number.
Example
#include <stdio.h>#include <math.h>
int main() { double number = 81.0; double result = sqrt(number);
printf("The square root of %.2f is %.2f\n", number, result);
return 0;}
Output
The square root of 81.00 is 9.00
Here, sqrt() is used to find the square root of a number. This kind of function is vital in scientific computing, game development, and other fields where mathematical operations are commonly used.
3. Input and Output Functions(<stdio.h>)
Functions for input and output operations, mainly dealing with file and console I/O.
- printf(): Outputs formatted string to the console.
- scanf(): Reads input from the console.
- fopen
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