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C Program – Basic

C Hello World Program

This program demonstrates how to write a simple "Hello, World!" program in C. It's the first step for beginners learning the C programming language.

Syntax

#include 

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

Hello, World!

C Program to Print Your Own Name

This program takes a string (your name) and prints it to the console.

Syntax

#include 

int main() {
    printf("My name is John Doe.\n");
    return 0;
}
Output

My name is John Doe.

C Program to Print an Integer Entered By the User

This program prompts the user to enter an integer and then displays the entered value.

Syntax

#include 

int main() {
    int number;
    printf("Enter an integer: ");
    scanf("%d", &number);
    printf("You entered: %d\n", number);
    return 0;
}
Output

Enter an integer: 5
You entered: 5

C Program to Add Two Numbers

This program demonstrates how to add two numbers provided by the user.

Syntax

#include 

int main() {
    int num1, num2, sum;
    printf("Enter two integers: ");
    scanf("%d %d", &num1, &num2);
    sum = num1 + num2;
    printf("Sum: %d\n", sum);
    return 0;
}
Output

Enter two integers: 4 5
Sum: 9

C Program to Check Whether a Number is Prime or Not

This program determines whether a given number is a prime number.

Syntax

#include 
#include 

bool isPrime(int num) {
    if (num <= 1) return false;
    for (int i = 2; i <= num / 2; i++) {
        if (num % i == 0) return false;
    }
    return true;
}

int main() {
    int number;
    printf("Enter a positive integer: ");
    scanf("%d", &number);

    if (isPrime(number))
        printf("%d is a prime number.\n", number);
    else
        printf("%d is not a prime number.\n", number);

    return 0;
}
Output

Enter a positive integer: 7
7 is a prime number.

Enter a positive integer: 8
8 is not a prime number.

C Program to Multiply Two Floating-Point Numbers

This program multiplies two floating-point numbers entered by the user.

Syntax

#include 

int main() {
    float num1, num2, product;
    printf("Enter two floating-point numbers: ");
    scanf("%f %f", &num1, &num2);

    product = num1 * num2;
    printf("Product: %.2f\n", product);

    return 0;
}
Output

Enter two floating-point numbers: 3.5 2.2
Product: 7.70

C Program to Print the ASCII Value of a Character

This program displays the ASCII value of a character entered by the user.

Syntax

#include 

int main() {
    char ch;
    printf("Enter a character: ");
    scanf(" %c", &ch);
    printf("ASCII value of %c: %d\n", ch, ch);
    return 0;
}
Output

Enter a character: A
ASCII value of A: 65

C Program to Swap Two Numbers

This program swaps the values of two numbers using a temporary variable.

Syntax

#include 

int main() {
    int a, b, temp;
    printf("Enter two integers: ");
    scanf("%d %d", &a, &b);

    temp = a;
    a = b;
    b = temp;

    printf("After swapping: a = %d, b = %d\n", a, b);
    return 0;
}
Output

Enter two integers: 10 20
After swapping: a = 20, b = 10

Alternatively, you can swap numbers without using a temporary variable:

Syntax

#include 

int main() {
    int a, b;
    printf("Enter two integers: ");
    scanf("%d %d", &a, &b);

    a = a + b;
    b = a - b;
    a = a - b;

    printf("After swapping: a = %d, b = %d\n", a, b);
    return 0;
}
Output

Enter two integers: 10 20
After swapping: a = 20, b = 10