程式語言 第三課 part2

/* * =========================================================================== * 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("請輸入要計算的圓半徑 (半徑需大於0):"); scanf("%f", &fRadius);
/* [b] : Check that the radius in greater than zero */
if( fRadius <= 0 ) { printf("ERROR >> 圓半徑必需大於0 \n"); exit (1); }
/* [c] : Compute Area of Circle */
fPi = 4.0*atan( 1.0 ); fArea = fPi*fRadius*fRadius;
/* [d] : Print Radius and Area */
printf("圓半徑 = %8.3f \n", fRadius ); printf("圓面積 = %8.3f \n", fArea );
return (0);}