Basic C programs (examples)

Very basic C programs examples

1. C program to print "Hello world" or any text.

#include<stdio.h>
int main() {
	printf("Hello, World!");
	return 0;
}

2. C program to add two numbers and display the sum.

#include<stdio.h>
main() {
	int a=5, b=7, sum;
	sum = a+b;
	printf("Sum = %d",sum);
	return 0;
}

3. C program take input of two numbers and add them and display the sum.

#include<stdio.h>
main() {
	int a, b, sum;
	printf("Enter two numbers: ");
	scanf("%d %d",&a, &b);
	sum = a+b;
	printf("Sum = %d",sum);
	return 0;
}

4. C program perform simple mathematical operations.

#include <stdio.h>
main() {
	int a, b, sum, sub, mul, div, mod;
	printf("Enter two numbers: ");
	scanf("%d %d",&a, &b);
	sum = a+b;	//for addition
	sub = a-b;	//for substraction
	mul = a*b;	//for multiplication
	div = a/b;	//for division
	mod = a%b;	//for finding reminder
	printf("%d + %d = %d\n",a, b, sum);
	printf("%d - %d = %d\n",a, b, sub);
	printf("%d x %d = %d\n",a, b, mul);
	printf("%d / %d = %d\n",a, b, div);
	printf("%d %% %d = %d",a, b, mod);
	return 0;
}

5. C program calculate area of circle taking radius as input radius.

#include <stdio.h>
main() {
	float r, area;
	printf("Enter the radius: ");
	scanf("%f",&r);
	area = 3.1415 * r *r;
	printf("Area = %f",area);
}     

6. C program calculate circumference of circle having radius as input radius.

#include <stdio.h>
main() {
	float r, circum;
	printf("Enter the radius: ");
	scanf("%f",&r);
	circum = 2*3.1415*r;
	printf("Area = %f",circum);
}     

[Any fool can write code that a computer can understand. Good programmers write code that humans can understand.] – Martin Fowler

Prepared by : Subash Gautam.