Writting a First Hello World Program in C

In this lesson, you will learn

• Hello World program in C
• Examples

Let’s go through the first Hello World program in C, followed by a line-by-line explanation of each part of the program.

#include<stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Output:

Hello, World

Explanation of Each Line

### 🔹 #include <stdio.h>

• #include is a preprocessor directive.

• <stdio.h> stands for Standard Input Output Header file.

• This line tells the compiler to include the standard I/O library, which contains the definition of the printf() function used later.

### 🔹 int main()

• main() is the starting point of every C program.

• int means the function will return an integer to the operating system.

• Every program must have one main() function, where execution begins.

### 🔹 {

• This opening curly brace { indicates the beginning of the function body.

• All the statements inside the function are enclosed in { }.

### 🔹 printf("Hello, World!\n");

• printf is a standard output function that displays text on the screen.

• "Hello, World!\n" is a string literal.

  • The text inside quotes is printed as is.

  • \n is an escape sequence that moves the cursor to a new line after printing.

• The ; is used to end the statement (very important in C).

### 🔹 return 0;

• This statement returns 0 from the main() function.

• In C, returning 0 typically means that the program executed successfully.

• It is passed back to the operating system.

### 🔹 }

• This closing brace } indicates the end of the function body.

Summary Table

Examples

Program 1: Add Two Numbers

#include<stdio.h>

int main() {
    int a = 5, b = 7, sum;
    sum = a + b;
    printf("Sum = %d\n", sum);
    return 0;
}

Output

Sum = 12

End of the lesson….enjoy learning.

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