Go4Expert - while loop and nested if statement problems

hi everyone. hope u'r all doin great 2day. i'm trying to a prob i have with loops
so far the code i've writtin was successfully built but my answers are not right . cld somebody please check this code and tell me why i'm getting wrong answers with it?

Code:

#include "stdafx.h"

#include <iostream>

#include <iomanip>

using namespace std;







int _tmain(int argc, _TCHAR* argv[])

{

    //declarations

    int operation;

    double CirRadius, CirArea, Base, Height, TriArea;

    const double PI = 3.14159;



    // menu

    cin >> operation;

    while (operation !=4)

    {

        if (operation == 1)

        {

            cin >> CirRadius;

              CirArea = PI * CirRadius * CirRadius;

            cout<<"The area of a circle with radius "<<CirRadius<<" is " <<setprecision(4)<<CirArea<<'\n\n';

            cin >> operation;

        }

        else if (operation == 2 || operation == 3)

        {

            cin >> Base;

            cin >> Height;

            TriArea = 0.5 * Base * Height;

            cout<<"The area of a triangle with base "<<Base<<" and height "<<Height<<" is "<<TriArea<<'\n\n';

            cin >> operation;

        }

        else if (operation == 5 || operation == 7)

        {

            cout<<"Error: "<<operation<<" is not a valid operation.\n\n";



        }

        

    }



    return 0;

}

heres the whole question

Geometry Calculator:
* Use nested if-else statements for all decision making in the program.
* Declare PI as a double constant with value 3.14159
* Use a while loop to repeat until the user types a 4 as shown below. If the operation code is not 1 through 4, then print an error message and go to the next data item.
* If a negative data value is entered by the user (or read from file), make it positive and use it.
* Use double for all your data variables and print all values with 4 decimal places.
* When the operation is 4, print "Thank you for using my calculator" and end the program.
* In the data given, the first figure is the operation value. An operation value of 1 refers a circle and the next value is the radius. An operation value of 2 or 3 refers to a triangle and the values after it are the base and height of the triangle. Operation values of 5 and 7 should show error messages

Code:

int operation;

// display the menu

cin >> operation;

while (operation != 4)

{

    // put your calculations here

    // display the menu

    cin >> operation;

}

OPERATIONS & DATA VALUES

1 4.58
2 6.34 5.8
3 7 -13
5
2 -6 19.4443
3 81.8 0.543
1 -8976
7
2 12.58 3
4

After you have the program running on the screen, change the I/O to file I/O. Your output should be as shown in the sample below, with a blank line between each output:

The area of a circle with radius 4.5800 is 14.3885
Error: 5 is not a valid operation
The area of a triangle with base 7.0000 and height 13.0000 is 45.5000
Thank you for using my calculator