find areas using function and case :

 #include<iostream>

#include<conio.h>

#include<math.h>

using namespace std;

void areaofcircle(void)

{

int radius;

cout<<"                TO FIND THE AREA OF CIRCLE :"<<endl;

cout<<"\n\n\tEnter the radius of circle:"<<ends;

cin>>  radius;

float area = 3.14*radius*radius;

cout<<"\n\n\t Area of circle: "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaoftriangle(void)

{

int base,height;

cout<<"\n\n            TO FIND THE AREA OF TRIANGLE:"<<endl;

cout<<"\n\n\tEnter the base: ";

cin>>base;

cout<<"\n\n\tEnter the haight: ";

cin>>height;

float area=0.5*base*height;

cout<<"\n\n\tArea of triangle : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofequilateraltriangle(void)

{

int base;

cout<<"\n\n            TO FIND THE AREA OF EQULATERAL TRIAGLE:"<<endl;

cout<<"\n\n\tLength of side is : ";

cin>>base;

float area=(float)(sqrt(3)*(base*base))/4;

cout<<"\n\n\tArea of Equilateral Triangle is : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofrectangle(void)

{

int base,height;

cout<<"\n\n                 TO FIND THE AREA OF RECTANGLE :"<<endl;

cout<<"\n\n\tEnter the length  of rectangle :";

cin>>base;

cout<<"\n\n\tEnter the breadth of rectangle :";

cin>>height;

float area=base*height;

cout<<"\n\n\tArea of rectangle is :"<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofsquare(void)

{

int base;

cout<<"\n\n                 TO FIND THE AREA OF SQUARE :"<<endl;

cout<<"\n\n\tEnter the side of square :";

cin>>base;

float area=base*base;

cout<<"\n\n\tArea of square is :"<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofrhombus(void)

{

int base , height;

cout<<"\n\n                 TO FIND THE AREA OF RHOMBUS :"<<endl;

cout<<"\n\n\tEnter the values of diagonal :"<<ends;

cin>>base>>height;

float area=(base*height)/2;

cout<<"\n\n\tArea of rhombus is : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofpentagon(void)

{

int base;

cout<<"\n\n                TO FIND THE AREA OF PENTAGON :"<<endl;

cout<<"\n\n\tEnter the length of side of pentagon :";

cin>>base;

float area=(sqrt(5*(5+2*sqrt(5))) * (base*base))/4;

cout<<"\n\n\tArea of Regular pentagon is : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofhexagon(void)

{

int base;

cout<<"\n\n               TO FIND THE AREA OF HEXAGON :"<<endl;

cout<<"\n\n\tEnter the length of side of hexagon : ";

cin>>base;

float area=(3*sqrt(3)*base*base)/2;

cout<<"\n\n\tArea of Regular hexagon is : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofheptagon(void)

{

float apothem,perimeter,area;

int base;

cout<<"\n\n              TO FIND THE AREA OF HEPTAGON :"<<endl;

cout<<"\n\n\tEnter the value of side of heptagon :";

cin>>base;

cout<<"\n\n\tEnter the value of apothem :";

cin>>apothem;

perimeter=7*base;

area=(perimeter*apothem)/2;

cout<<"\n\n\tArea of Regular heptagon : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaofoctagon(void)

{

int base;

cout<<"\n\n             TO FIND THE AREA OF OCTAGON :"<<endl;

cout<<"\n\n\tEnter the length of side of octagon : ";

cin>>base;

float area=2*(1+sqrt(2))*base*base;

cout<<"\n\n\tArea of octagon is : "<<area;

getch();

cout<<"\n________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

}

void areaoftrapezoid(void)

{

int base,radius,height;

cout<<"\n\n            TO FIND THE AREA OF TRAPEZOID :"<<endl;

cout<<"\n\n\tEnter the value of bases : "<<endl;

cin>>base>>radius;

cout<<"\n\n\tEnter the value of height : ";

cin>>height;

float area=(float)((base*radius)*height)/2;

cout<<"\n\n\tArea of Trapezoid is :"<<area;

getch();

cout<<"\n............................END............................................";

}

int main()

{

int a,i;

cout<<"________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

cout<<"\n\t\tEnter 1 for area of circle :"<<endl;

cout<<"\n\t\tEnter 2 for area of triangle :"<<endl;

cout<<"\n\t\tEnter 3 for area of equilateral triangle :"<<endl;

cout<<"\n\t\tEnter 4 for area of rectangle :"<<endl;

cout<<"\n\t\tEnter 5 for area of square :"<<endl;

cout<<"\n\t\tEnter 6 for area of rhombus :"<<endl;

cout<<"\n\t\tEnter 7 for area of pentagon :"<<endl;

cout<<"\n\t\tEnter 8 for area of hexagon :"<<endl;

    cout<<"\n\t\tEnter 9 for area of heptagon :"<<endl;

    cout<<"\n\t\tEnter 10 for area of octagon :"<<endl;

    cout<<"\n\t\tEnter 11 for area of trapezoid :"<<endl;

cin>>i;

cout<<"________________________________________________________________________"<<endl;

cout<<"________________________________________________________________________"<<endl;

switch(i)

{

case 1:

areaofcircle();

break;

case 2:

areaoftriangle();

break;

case 3:

areaofequilateraltriangle();

break;

case 4:

areaofrectangle();

break;

case 5:

areaofsquare();

break;

case 6:

areaofrhombus();

break;

case 7:

areaofpentagon();

break;

case 8:

areaofhexagon();

break;

case 9:

areaofheptagon();

break;

case 10:

areaofoctagon();

break;

case 11:

areaoftrapezoid();

        break;

    default :

cout<<"Please Enter the valid key for areas:";

    

}

return 0;

}