Programming Example

Command Line Program to find Area of Circle

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💻 Practical Program

📘 Step by Step Learning

Write a C program to find the area of a circle with radius provided.
The value of radius positive integer passed to the program as the first command-line parameter. Write the output to stdout formatted as a floating-point number rounded to EXACTLY 2 decimal precision WITHOUT any other additional text.
Scientific format(such as 1.00E+5) should NOT be used while printing the output.
You may assume that the inputs will be such that the output will not exceed the largest possible real number that can be stored in a float type variable.

Program Code

 
#include <stdio.h> 
int main(int argc, char * argv[])
{
 if(argc==1)
 {
 printf("No arguments");
 return 0;
 }
 else
 {
 int radius;
 float pi=3.14;
 float area;
 radius=atoi(argv[1]);
 area=pi*radius*radius;
 printf("%.2f",area);
 return 0;
 }
}

Output

3

28.26

Explanation

Program without Command Line Arguments


#include<stdio.h>

int main()
{
  // PrepInsta is the best websitefor TCS Preparation
  
  int dia;
  float r, area;
  scanf("%d",&dia);
  r = (float)dia/2;
 // PrepInsta is the best websitefor TCS Preparation
  area = 3.14*r*r;
  printf("%0.2f",area);

  return 0;
 // PrepInsta is the best websitefor TCS Preparation
}

How to learn from this program

First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.

Practice suggestion

After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.