Area of Circle Using Command Line Arguments

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.

Note: Please go through Command Line Arguments Post before preparing for these questions. The theory there  for TCS command line Program will help you in better understanding .

#include<stdio.h>
#include<stdlib.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;
 }
}