C++ Program
#include <iostream> #define PI 3.14159 using namespace std; float AreaOfCircle(float radius); float AreaWithDiameter(float diameter); int main() { float radius,diameter,circleArea; char choice='0'; cout<<"\n\t\t\tFind Area Of Circle:"<<endl; for (;choice!='1'&&choice!='2';) { cout<>choice; if(choice!='1'&&choice!='2') cout<<"\n\t\tEnter a VALID Option "; } if(choice=='1') { cout <>radius; circleArea=AreaOfCircle(radius); } else if(choice=='2') { cout <>diameter; circleArea=AreaWithDiameter(diameter); } cout<> "<<circleArea<<endl; return 0; } float AreaOfCircle(float radius) { return (PI*(radius*radius)); } float AreaWithDiameter(float diameter) { return (AreaOfCircle(diameter/2)); }