C – Basic Program

                                                                                            

We are going to learn a simple “Hello World” C program in this section. Also, all the below topics are explained in this section which are the basics of a C program.

1. C Basic Program:

 #include <stdio.h>

int main()

{

     /* Our first simple C basic program */

     printf("Hello World! ");

     getch();

     return 0;

}

Output:

Hello World!

Explanation for above C basic Program:

Let’s see all the sections of the above simple C program line by line.

S.no	Command	Explanation
1	#include <stdio.h>	This is a preprocessor command that includes standard input output header file(stdio.h) from the C library before compiling a C program
2	int main()	This is the main function from where execution of any C program begins.
3	{	This indicates the beginning of the main function.
4	/*_some_comments_*/	whatever is given inside the command “/*   */” in any C program, won’t be considered for compilation and execution.
5	printf(“Hello_World! “);	printf command prints the output onto the screen.
6	getch();	This command waits for any character input from keyboard.
7	return 0;	This command terminates C program (main function) and returns 0.
8	}	This indicates the end of the main function.

Write a program in C Program to find area and circumference of circle

#include<stdio.h>

int main()
{
int rad;
float PI=3.14,area,ci;

printf("nEnter radius of circle: ");
scanf("%d",&rad);

area = PI * rad * rad;
printf("nArea of circle : %f ",area);

ci = 2 * PI * rad;
printf("nCircumference : %f ",ci);

return(0);
}

Output :

Enter radius of a circle : 1
Area of circle : 3.14
Circumference  : 6.28

Explanation of Program :

In this program we have to calculate the area and circumference of the circle. We have following 2 formulas for finding circumference and area of circle.

Area of Circle = PI * R * R

and

Circumference of Circle = 2 * PI * R

In the above program we have declared the floating point variable PI whose value is defaulted to 3.14.We are accepting the radius from user.

printf("nEnter radius of circle: ");
scanf("%d",&rad);