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i cant get this program to work

Gaylle (9)
hi everyone. i hope y'all r doin great today. i saw this prob somewhere and tried to solve it but being such a rookie, my nested if statements just wont work. can somebody please try it out and show me how it can be done?

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


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
R0N (13)
I solved your problem, the next program does the trick :)

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// geometry.cpp : main project file.
#include "stdafx.h"  // Visual Studio Specific library
#include <iostream>
#include <string>
#include <fstream>
#include <exception>

using namespace std;

const double pi = 3.14159;

class geometry
{
	double width, height, radius;
public:
	geometry();
	~geometry();
	void start(char*);
	void calculate_rectangle();
	void calculate_triangle();
	void calculate_circle();
};

geometry::geometry()
{
	cout.setf(ios::fixed,ios::floatfield);
	cout.precision(4);
	this->width=0;
	this->height=0;
	this->radius=0;
};

geometry::~geometry()
{
	cout<<"Thank you for using my calculator\n";
};

void geometry::start(char* filename)
{
	char * cstring;
	char * piece1 = "";
	char * piece2 = "";
	char * piece3 = "";
	fstream file;

	string instruction;
	char option;
	bool exit=false;
	if(strlen(filename)>0)
	{
		file.open((const char*) filename, ios::beg | ios::in );
		if(!file.is_open())
		{
			throw;
		}
	}

	while(!exit)
	{
		if(strlen(filename)>0)
		{
			if(file.eof()) exit=true;
			getline(file,instruction);
		}
		else
		{
			getline(cin,instruction);
		}
		if(instruction.size()!=0)
		{
			option=instruction.at(0);

			cstring = new char[instruction.size()+1];
			strcpy(cstring,instruction.c_str());

			piece1 = strtok(cstring, " ");
			if(piece1!=NULL);
			piece2 = strtok(NULL, " ");
			if(piece2!=NULL&&(option!='3'||option!='4'));
			piece3 = strtok(NULL, " ");

			if(piece2!=NULL&&option!='4')
			{
				this->width=atof(piece2);
				this->radius=atof(piece2);
				if(piece3!=NULL&&(option!='3'||option!='4'))
				{
					this->height=atof(piece3);
				}
				if(this->width<0.0)  this->width*=-1.0;
				if(this->radius<0.0) this->radius*=-1.0;
				if(piece3!=NULL&&(option!='3'||option!='4'))
				{
					if(this->height<0.0) this->height*=-1.0;
				}
			}
			if(((option=='1'||option=='2')&&piece2!=NULL&&piece3!=NULL)||
				(option=='3'&&piece2!=NULL)||
				(option=='4'))
			{
				switch (option)
				{
					case '1': this->calculate_rectangle();break;
					case '2': this->calculate_triangle();break;
					case '3': this->calculate_circle();break;
					case '4': exit=true;break;	
				}
				this->width=0.0;
				this->height=0.0;
				this->radius=0.0;
			}
			else
			{
				cout<<"error: "<<instruction<<" is not a valid operation\n";
			}
			delete cstring;
		}
	}
	if(file.is_open())
	{
		file.close();
	}
};

void geometry::calculate_rectangle()
{
	cout<<"the area of a rectangle with width "<<this->width
		<<" and height "<<this->height
		<<" is "<<this->width*this->height
		<<endl;
};

void geometry::calculate_triangle()
{
	cout<<"the area of a triangle width base "<<this->width
		<<" and height "<<this->height
		<<" is "<<this->width*this->height/2
		<<endl;
};

void geometry::calculate_circle()
{
	cout<<"the area of a circle with radius "<<this->radius
		<<" is "<<this->radius*this->radius*pi
		<<endl;
};

int main(int argc, char* argv[])
{
	char * filename = "";
	geometry * calculator = new geometry();

	if(argc==2)
	{
		filename=argv[1];
	}
	try
	{
		calculator->start(filename);
	}
	catch(...)
	{
		cout<<"file not found\n";
	}
	delete calculator;
    return 0;
}


With regards, Ronnie van Aarle.
R0N (13)
By the way, use it like:

geometry

or

geometry <filename_of_file_with_instructions>
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