Ask the user to input the radius and compute of the area of circle given the pie equals 3.14 in dev-c plus plus?

Answer 1

#include <iostream>

// Required to calculate pi more accurately:

//#include <math.h>

int main()

{

const double pi = 3.14;

// To calculate pi more accurately, use:

// const double pi = 4*atan(1.0);

double r;

while( 1 )

{

printf( "Calculate the area of a circle.\n" );

printf( "Enter 0 to exit.\n" );

printf( "Enter the circle's radius: " );

if( std::cin >> r )

{

if( !r )

{

printf( "\n" );

break;

}

printf( "Area of circle is: %.2f\n\n", pi * r * r );

}

else

{

printf( "Invalid input. Please try again.\n\n" );

std::cin.clear();

while( std::cin.get() != '\n' ) ;

}

}

return( 0 );

}