Temperature Conversion Program - Still a Rookie

A

AsheeG87

Hey Everyone~
I'm still a C++ Rookie so please bear with me on this.
I'm doing a temperature conversion program with prototype functions.
Basicly, I was wondering if some of you would take a look at my code
and critique it for me. I'm mostly concerned with how prototype
functions work and if I designed them correctly in my code.
Your participation would be greatly appreciated!

My Code:

#include "stdafx.h"
#include <iostream>
#include <cstdlib>

double FahrenheittoCelsius(double)= 0.0; //Function Prototype
double CelsiustoFahrenheit(double)= 0.0;

int _tmain(int argc, _TCHAR* argv[])
{
double tempFahrenheit, tempCelsius;
double temp;
char f;
char c;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << " Fahrenheit or Celsius?"; // If user does not specify f or c
ask them
if (temp == f)
{
c = FahrenheittoCelsius;
cout << f " degrees Fahrenheit is" c " degrees celsius ";
cout << " Continue? ";

else
f = CelsiustoFahrenheit;
cout << c " degrees Celsius is " f " degrees Fahrenheit ";
cout << " Continue? ";

}


return temp;
}
double FahrenheitoCelsius (double f)
{
return (f - 32) * (5.0/9);
}
double CelsiustoFahrenheit (double c)
{
return (9/5.0 * c) + 32;
}
 
I

Ian Collins

Hey Everyone~
I'm still a C++ Rookie so please bear with me on this.
I'm doing a temperature conversion program with prototype functions.
Basicly, I was wondering if some of you would take a look at my code
and critique it for me. I'm mostly concerned with how prototype
functions work and if I designed them correctly in my code.
Your participation would be greatly appreciated!

My Code:
I assume you haven't tried to compile this!

Some hints:
#include "stdafx.h"

Non-standard header.
#include <iostream>
#include <cstdlib>

double FahrenheittoCelsius(double)= 0.0; //Function Prototype
double CelsiustoFahrenheit(double)= 0.0;
These are syntax errors, not prototypes. Loose the = 0.0.
int _tmain(int argc, _TCHAR* argv[])

That's _TCHAR? Use

int main( int argc, char* argv[] )

{
double tempFahrenheit, tempCelsius;
double temp;
char f;
char c;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << " Fahrenheit or Celsius?"; // If user does not specify f or c
ask them
if (temp == f)

Where is f assigned?
{
c = FahrenheittoCelsius;

Here you attempt to assign a function to a char, which is a very strange
thing to do! Did you mean to write

c = FahrenheittoCelsius( temp );
cout << f " degrees Fahrenheit is" c " degrees celsius ";
cout << " Continue? ";
missing }
else

missing {
 
J

Jim Langston

Hey Everyone~
I'm still a C++ Rookie so please bear with me on this.
I'm doing a temperature conversion program with prototype functions.
Basicly, I was wondering if some of you would take a look at my code
and critique it for me. I'm mostly concerned with how prototype
functions work and if I designed them correctly in my code.
Your participation would be greatly appreciated!

My Code:

#include "stdafx.h"
#include <iostream>
#include <cstdlib>

double FahrenheittoCelsius(double)= 0.0; //Function Prototype

This is not a pure virtual method. It is a function prototype. It should
look like this:
double FarenheitToCelcius(double);
double CelsiustoFahrenheit(double)= 0.0;

double CelciusToFarenheit(double);
int _tmain(int argc, _TCHAR* argv[])

This is non standard, becuase you did a windows project and are using
standard headers. That is frowned upon in this newsgroup.

project->properties->c/C++->Precompiled Headers
Change Create/Use Precompiled Header to Not Using Precompiled Header.
Then remove stdafx.cpp from your project. Change your main to:
int main()
{
double tempFahrenheit, tempCelsius;
Better to call these Farenheit and Celcius so you don't confuse yourself.

double Farenheit, Celcious;
double temp;
char f;
char c;

These are not the characters 'f' and 'c' but variables of type char that are
called f and c. You can get rid of these.
cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << " Fahrenheit or Celsius?"; // If user does not specify f or c
ask them
if (temp == f)

You are asking if temp == f. temp is a double. f is a char. I think you
actually wanted to ask the user but forgot to do it.

char torf;
cin >> torf;

if ( torf == 'f' )
{
c = FahrenheittoCelsius;

You need to call a function there. Your prototype is:
double FarenheitToCelcius(double);
so it would be:

Celcius = FarenheitToCelcius( temp );
cout << f " degrees Fahrenheit is" c " degrees celsius ";
That ain't going to work. It should be:
cout << Farenheit << " degrees Fahrenheit is" << Celcius << " degrees
celsius ";
cout << " Continue? ";

else
f = CelsiustoFahrenheit;
cout << c " degrees Celsius is " f " degrees Fahrenheit ";

See comments for converting from FarenheitToCelcius and fix this to reflect.
cout << " Continue? ";

}


return temp;
}
double FahrenheitoCelsius (double f)
{
return (f - 32) * (5.0/9);
}
double CelsiustoFahrenheit (double c)
{
return (9/5.0 * c) + 32;
}

Okay, try all tis, then actually try to compile it. You'll get compilation
errors variables not found, etc.. Fix the errors. If you still get stuck
post again with your new fixed code.
 
A

AsheeG87

You are a lot of help! And...I feel dumb about some of the mistakes
that I made. I have no clue where I came up with that. But, I'm still
learning. So, here we go. I am having a problem debugging. It won't
execute the program. So, I can build and see the errors that come up
but it won't execute. What am I missing?

Here is my *NEW* code:

// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";
cout << " Continue? ";
if
tempFahrenheit = CelsiustoFahrenheit(temp);
cout << tempCelsius << " degrees Celsius is " << tempFahrenheit << "
degrees Fahrenheit";
cout << " Continue? ";
}

return 0;
}
double FahrenheittoCelsius (double f)
{
return (f - 32) * (5.0/9);
}
double CelsiustoFahrenheit (double c)
{
return (9/5.0 * c) + 32;
}
 
I

Ian Collins

You are a lot of help! And...I feel dumb about some of the mistakes
that I made. I have no clue where I came up with that. But, I'm still
learning. So, here we go. I am having a problem debugging. It won't
execute the program. So, I can build and see the errors that come up
but it won't execute. What am I missing?

Here is my *NEW* code:
Which *still* shouldn't compile!
// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"

Loose this.
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";
cout << " Continue? ";

missing }

missing condition and {
 
A

ajk

#include "stdafx.h"
#include <iostream>
#include <cstdlib>

double FahrenheittoCelsius(double)= 0.0; //Function Prototype
double CelsiustoFahrenheit(double)= 0.0;

double FahrenheittoCelsius(double arg);
double CelsiustoFahrenheit(double arg);
int _tmain(int argc, _TCHAR* argv[])
{

fine, visual studio will set correct character type depending on
unicode or multibyte but for now use char instead, since you are
learning.
double tempFahrenheit, tempCelsius;
double temp;
char f;
char c;

initialize all variables always, this can help you in the future,
preferably initialize them to some invalid - for your purposes -
value.
cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
ok

cout << " Fahrenheit or Celsius?"; // If user does not specify f or c
ask them
if (temp == f)
{

temp is of type double and f is of type char - what are you doing
here? looks like you have misstakenly taken then variable name f as
the variable value 'f'.

instead use

const char celsius = 'c';
const char fahrenheit = 'f';
char choice;

cin >> choice;
if ( choice == celsius )
{
}

c = FahrenheittoCelsius;
cout << f " degrees Fahrenheit is" c " degrees celsius ";
cout << " Continue? ";

else
f = CelsiustoFahrenheit;
cout << c " degrees Celsius is " f " degrees Fahrenheit ";
cout << " Continue? ";

}


return temp;
}
double FahrenheitoCelsius (double f)
{
return (f - 32) * (5.0/9);
}
double CelsiustoFahrenheit (double c)
{
return (9/5.0 * c) + 32;
}

hth/ajk
 
A

ajk

// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );

temp is undefined, it hasn't been set to a value
 
J

Jim Langston

You are a lot of help! And...I feel dumb about some of the mistakes
that I made. I have no clue where I came up with that. But, I'm still
learning. So, here we go. I am having a problem debugging. It won't
execute the program. So, I can build and see the errors that come up
but it won't execute. What am I missing?

Here is my *NEW* code:

// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"

You don't need to include stdafx.h anymore, that was part of precompiled
headers. Delete that line.
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;


cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> corf;

You send the message to the console for the user to enter the Temperature,
but then you have them input if it's celsius or centigrade.

This should be:

cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << "Celcius or Farenheit? ";
cin >> corf;
if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";
cout << " Continue? ";
if

Somehow you cut off this line. This should probably be:
if ( corf == 'c' )
{
 
D

Default User

Jim Langston wrote:

You send the message to the console for the user to enter the
Temperature, but then you have them input if it's celsius or
centigrade.

This should be:

cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << "Celcius or Farenheit? ";
cin >> corf;


This isn't a very robust design. There are all kinds of unused
characters left hanging around. I'd recommend reading in the entire
line and examining the first character.




Brian
 
A

AsheeG87

Alright guys....
I agree with you that stdafx.h does not need to be included but it
won't compile without it.
Ok....so,I started playing around with it and I got the program to
finally compile and it is working fairly ok.
The program will exit when I enter a value because temp,
tempFahrenheit, and tempCelsius have not been intialized. When I set
it to 0 I still get the same problem. Any ideas?
Oh by the way....here is the updated code from this afternoon.

// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;



cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << " Fahrenheit or Celsius? ";
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";
cout << " Continue? ";

}
if (corf == 'c')
{
tempFahrenheit = CelsiustoFahrenheit(temp);
cout << tempCelsius << " degrees Celsius is " << tempFahrenheit << "
degrees Fahrenheit";
cout << " Continue? ";

}

return temp;
}
double FahrenheittoCelsius (double f)
{
return (f - 32) * (5.0/9);
}
double CelsiustoFahrenheit (double c)
{
return (9/5.0 * c) + 32;
}
 
I

Ian Collins

Alright guys....
I agree with you that stdafx.h does not need to be included but it
won't compile without it.
Nonsense.

Ok....so,I started playing around with it and I got the program to
finally compile and it is working fairly ok.
The program will exit when I enter a value because temp,
tempFahrenheit, and tempCelsius have not been intialized. When I set
it to 0 I still get the same problem. Any ideas?

It will exit because it falls out of main, there is nothing after your
last output line.
Oh by the way....here is the updated code from this afternoon.

// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>

using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;

cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;
cout << " Fahrenheit or Celsius? ";
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";

You don't initialise tempFahrenheit, so garbage will be output, same
fortempCelsius in the next block.
cout << " Continue? ";
You could do the above after the if() blocks to avoid duplication.
}
if (corf == 'c')
{
tempFahrenheit = CelsiustoFahrenheit(temp);
cout << tempCelsius << " degrees Celsius is " << tempFahrenheit << "
degrees Fahrenheit";
cout << " Continue? ";

}

return temp;

This isn't a legal return value from main, 0, EXIT_SUCCESS and
EXIT_FAILURE are the only portable returns.
 
A

AsheeG87

It will exit because it falls out of main, there is nothing after your
last output line.



You don't use anything from <cstdlib>, so it can go as well.










You don't initialise tempFahrenheit, so garbage will be output, same
fortempCelsius in the next block.


You could do the above after the if() blocks to avoid duplication.


This isn't a legal return value from main, 0, EXIT_SUCCESS and
EXIT_FAILURE are the only portable returns.

I hear ya...but it won't go any further until I intialize that
variable.
 
I

Ian Collins

You don't initialise tempFahrenheit, so garbage will be output, same
fortempCelsius in the next block.



You could do the above after the if() blocks to avoid duplication.



This isn't a legal return value from main, 0, EXIT_SUCCESS and
EXIT_FAILURE are the only portable returns.
Please don't quote signatures, or that google quoted text crap.
I hear ya...but it won't go any further until I intialize that
variable.
What won't? Looking though what you posted, it will run through once,
then exit.
 
D

Default User

Alright guys....
I agree with you that stdafx.h does not need to be included but it
won't compile without it.

That's only because you started with the wrong sort of project
initially. If you can't fix it by changing the project settings, start
over with a new "console" project and include that file in the new
project.




Brian
 
O

Old Wolf

Nonsense.

How do you know whether or not the OP's compiler will compile
code without that line? In fact it seems likely from his
description that the compilation fails when he deletes it.
You don't initialise tempFahrenheit, so garbage will be output

The behaviour will be undefined -- it could crash the program, etc.
This isn't a legal return value from main, 0, EXIT_SUCCESS and
EXIT_FAILURE are the only portable returns.

Other return values are legal. The only 'problem' is that the
operating system may not be able to determine whether the
program succeeded or failed.
 
I

Ian Collins

Old said:
How do you know whether or not the OP's compiler will compile
code without that line? In fact it seems likely from his
description that the compilation fails when he deletes it.
He made no mention of a complier, just that the code wouldn't compile
without it. On my system, it won't compile with it!
 
J

Jim Langston

Alright guys....
I agree with you that stdafx.h does not need to be included but it
won't compile without it.

Make sure you remove the stdafx.cpp from the progject and it should. This
code does for me in VC++ .net 2003 without stdafx.h
Ok....so,I started playing around with it and I got the program to
finally compile and it is working fairly ok.
The program will exit when I enter a value because temp,
tempFahrenheit, and tempCelsius have not been intialized. When I set
it to 0 I still get the same problem. Any ideas?
Oh by the way....here is the updated code from this afternoon.

Run the program with ctrl-F5 instead of F5 and you will get a
Press any key to continue...
after the program runs allowing you to see the output. This is Microsoft
specific.

Personally, I just make it wait in code by putting at the end of main
something on the line of:
std::string wait;
std::getline( std::cin, wait );
// Temperature.cpp : Defines the entry point for the console
application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

double FahrenheittoCelsius(double); //Function Prototype
double CelsiustoFahrenheit(double);

int main()
{
double tempFahrenheit, tempCelsius;
double temp;
char corf;



cout << " Enter the Temperature: "; //Prompt user to enter temp
cin >> temp;

Okay, the temperature is entered into a variabled called "temp".
cout << " Fahrenheit or Celsius? ";
cin >> corf;

if (corf == 'f')
{
tempCelsius = FahrenheittoCelsius( temp );
cout << tempFahrenheit << " degrees Fahrenheit is" << tempCelsius
<< " degrees celsius ";

The variable "tempFahrenheit" is not being used. The value was stored in
temp, not tempFahrenheit.
cout << temp << " degrees Fahrenheit is" << tempCelsius << " degrees
celsius ";
}
if (corf == 'c')
{
tempFahrenheit = CelsiustoFahrenheit(temp);
cout << tempCelsius << " degrees Celsius is " << tempFahrenheit << "
degrees Fahrenheit";

Same here, output temp, not tempCelsius.
 
J

James Kanze

This isn't a very robust design. There are all kinds of unused
characters left hanging around. I'd recommend reading in the entire
line and examining the first character.

The first non-blank character, and then verifying that there
aren't any other non-blanck characters in the line:).
 
J

James Kanze

Nonsense.

Worse. On my systems, it won't compile with it.

[...]
This isn't a legal return value from main, 0, EXIT_SUCCESS and
EXIT_FAILURE are the only portable returns.

Just a nit: it's legal, temp is a double, and a double converts
implicitly to an int. It doesn't make any sense, and the
results are very much implementation defined, but it is legal.
 
I

Ian Collins

James said:
Just a nit: it's legal, temp is a double, and a double converts
implicitly to an int. It doesn't make any sense, and the
results are very much implementation defined, but it is legal.
You're right, I should have written "portable" rather than "legal".

*Please* fix this - it's a pain to have to keep manually trimming your
signature.
 

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