程式語言 第三課 part1

/*
* ===========================================================================
* Compute Area of a Circle : Coefficients are defined in main program.
* : Radius and area of circle are printed to screen.
*
* Copyright (C) 1998 by Mark Austin and David Chancogne.
*
* This software is provided "as is" without express or implied warranty.
* Permission is granted to use this software on any computer system,
* and to redistribute it freely, subject to the following restrictions:
*
* 1. The authors are not responsible for the consequences of use of
* this software, even if they arise from defects in the software.
* 2. The origin of this software must not be misrepresented, either
* by explicit claim or by omission.
* 3. Altered versions must be plainly marked as such, and must not
* be misrepresented as being the original software.
* 4. This notice is to remain intact.
*
* Written by: Mark Austin January, 1994
* ===========================================================================
*/
#include /* Standard Input/Output function declarations */
#include /* Math functions, such as sqrt(x), and constant M_PI */
#include
int main( void ) {
float fRadius; /* Radius of circle */
float fArea; /* Area of circle */
float fPi; /* Variable for "pi" */
/* [a] : Prompt User for "radius of circle" */
printf("============================================\n");
printf("Please input the circle radius (Radius > 0):");
scanf("%f", &fRadius);
/* [b] : Check that the radius in greater than zero */
if( fRadius <= 0 ) {
printf("ERROR >> Circle radius must be greater than zero\n");
exit (1);
}
/* [c] : Compute Area of Circle */
fPi = 4.0*atan( 1.0 );
fArea = fPi*fRadius*fRadius;
/* [d] : Print Radius and Area */
printf("Radius of Circle = %8.3f \n", fRadius );
printf("Area of Circle = %8.3f \n", fArea );
return (0);
}