Large project how to seprate definition and declaration?

[Hassan Syed1]

Thank you everyone for your reply. Can you post in the code form like i showed in my 2nd post. If any link available about explaining this thing please share with me

[Lost User]

Header files just allow the declaration of constants, classes and functions that may be required to be used in more than one implementation file. The implementation (.c or .cpp) then includes the header file, allowing the compiler to have the declarations for any items that the C code uses. See why header files in c - Google Search[^] for further discussions on the subject.

[leon de boer]

Okay so this is your Calculation.h file ... which is only changed by removing the two include which are not needed

#ifndef _CALCULATION_H
#define _CALCULATION_H

void input_Func(void); //Input function of text.
void input_Area(void); //Input function of Area.
void input_Trap(void); //Input function of Trapezoid.
float rectangle_Area (float , float); //Declaration for Rectangle Area.
float trapezoid_Area (float , float, float); //Declaration for Trapezoid Area.

#endif

So now you must provide all that in a Calculation.cpp file which would be all the code below. So here are the functions you provided but notice I have marked the errors on the 2 functions Input_Area & Input_Trap So currently only 3 of your 5 functions are correct

#include "calculation.h" // include you header file

//Calculation of Rectangle Area.
float rectangleArea (float width, float length)
{
float Area_Rectange = 0;
Area_Rectange = width * length;
return (Area_Rectange);
}

//Calculation of Trapezoid Area.
float trapezoidArea (float base1, float base2, float height)
{
float Area_Trapezoid = 0;
Area_Trapezoid = ((base1 + base2)/2) * height;
return (Area_Trapezoid);
}

//Dealing with the input and output of data
void input_Func(void)
{
cout << "\n\nEnter 1 to calculate the area of Rectangle" << endl;
cout << "Enter 2 to calculate the area of a Trapezoid" << endl;
cout << "\n\nEnter your choice : ";
cin >> choice;
}

// YOU HAVE SERIOUS ERRORS IN THE TWO FUNCTION CODES BELOW

//Dealing with input of Rectangle
float input_Area(void) // *** ERROR *** YOUR HEADER HEADER FILE IS ==== > void input_Area(void); WHICH IS IT THEY MUST MATCH??????
{
float width = 0, length = 0, answer = 0;
cout << "Enter the width of rectangle :";
cin >> width;
cout << "Enter the length of rectangle :";
cin >> length;
answer = rectangleArea(width, length);
cout << "The area of Rectangle is : " << answer << endl;

break; // <<==== ***** ERROR ***** WHAT ARE YOU BREAKING FROM

/// ***** ERROR *****
// There is another problem here you have not returned anything
// You declare you are going to return a float and don't .. You put this === > float input_Area(void)
//
// I think you may want to return the variable Answer but your code matches
// the header file returning nothing so I am confused what you are doing
//
// You need to be clear are you returning a float or not and fix it
}

//D

[Hassan Syed1]

Can i have multiple declaration files for different functions. For example; can I have a .cpp file for having input of data and can have a separate file for calculation of data? Is it a correct approach which professional follows? Actually I am confused because of declaration and definitions in septate files. When I write whole code in main it works well as soon as put the code in separate files I started getting error. I removed the .cpp file as I told above and got that concept clear that NEVER include .cpp file in .h header file. I am still getting some function calling error. I am just 1 step away to know where the problem is coming in function call. Please someone correct that portion. i already removed the break from the function as it was mentioned and also got the logical reason behind removing it. Actually I added that break in structure but as I just copy pasted the code in functions I copied it along with it :(

[David Crow]

Hassan Syed1 wrote:

When I write whole code in main it works well as soon as put the code in separate files I started getting error.

Which means your compiler/linker options are not correct, but since you failed to share those errors, we can only guess.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

[leon de boer]

There Errors are explained above your header file declaration does not match your .cpp file. Even in a single file your code for Input_area and Input_trap are both bad and wrong. You will have several warnings which you are just ignoring I take it. Those warnings are real and pointing to a problem you need to fix, which becomes fatal when you turn it to a unit. You declare this in calculation.h

void input_Area(void); //Input function of Area.

You have this in your calculation.cpp

float input_Area(void){

LOOK AT THEM .. THEY ARE NOT THE SAME .. the return declare (1st word) differs ... THAT IS YOUR FIRST PROBLEM WITH THE .H FILE Again we repeat the declaration in the .H file must be EXACTLY the same as the interface actually in the .CPP file. THERE IS NO EXCEPTION TO THIS RULE .... EVER So the .H file could be changed to

float input_Area(void); //Input function of Area.

OR ... the .CPP file could be changed to

void input_Area(void){

I can't work out which definition is correct because you don't actually return anything from input_area. Either could be correct because your code has a big error I can't work out which is right. You have the same problem on float input_Trap. You declared you are returning a float but don't return anything, do you understand what I am saying when I say that????? Even in one big file you will be getting a 2 warnings, something like "function does not return value". I am struggling why you can't see the problem because you did it correctly in rectangleArea and trapezoidArea, so you know how to return a value when you declare it. So on your code you got right lets mark where you return a float.

float rectangleArea (float width, float length) // * PT1 ... HERE YOU DECLARE YOU ARE RETURNING A FLOAT .. the first word is FLOAT not VOID
{
float Area_Rectange = 0;
Area_Rectange = width * length;
return (Area_Rectange); // *** HERE YOU RETURN A FLOAT ... which is exactly what you said at PT1 ... HENCE THIS CODE IS CORRECT
}

Now look at Input_area and Input_trap the word return and some value doesn't appear in the code BUT you declared you are returning a float. The compiler and I are both confused with what you are doing. If you declare a float return, then please return one. If you don't want to return a float then change the first word on the declare to void (which matches what you have in the .H file). On the other issue yes we can mov

[Hassan Syed1]

This was the whole code from main file. Please divide it in module form like professional people do so that I can exactly see the problem in my understanding of dividing the project into moduler form

/*

Name = Syed Sibt E Hassan
Registration Number = MC160201226

1. Input from the user
2. Function Calls to reactangle and trapezoid
3. Exit loop when input is not 'Y' || 'y'
   */

#include
using namespace std;

float rectangleArea (float , float); //Declaration for Rectangle Area
float trapezoidArea (float , float, float); //Declaration for Trapezoid Area.

int main()
{
int choice = 0;
char tryagain = 0;
do
{
cout << "\n\nEnter 1 to calculate the area of Rectangle" << endl;
cout << "Enter 2 to calculate the area of a Trapezoid" << endl;
cout << "\n\nEnter your choice : ";
cin >> choice;
switch(choice)
{
//Dealing with area of Rectangle.
case 1:
{

                float width = 0.0, length = 0.0, answer = 0.0;
                cout << "Enter the width of rectangle :";
                cin >> width;
                cout << "Enter the length of rectangle :";
                cin >> length;
                answer = rectangleArea(width, length); //Function Call to Rectangle
                cout << "The area of Rectangle is : " << answer << endl;
                break;
            }

                     //Dealing with area of Trapezoid.
        case 2:
            {

                float base1 = 0.0, base2 = 0.0, height = 0.0, answer = 0.0;
                cout << "Enter base1 of trapezoid : ";
                cin >> base1;
                cout << "Enter base2 of trapezoid : ";
                cin >> base2;
                cout << "Enter the height of trapezoid : ";
                cin >> height;
                answer  = trapezoidArea(base1, base2, height); //Function Call to Trapezoid
                cout << "The area of Trapezoid is : " << answer << endl;
                break;
            }

        default:{
            cout << "Neither 1 nor 2 entered." << endl;
            }
        }

        cout << "\\n Do you want to do another calculation? : ";
        cin >> tryagain;
    }while (tryagain == 'Y' || tryagain == 'y');

return

[David Crow]

How hard is it to put the function signatures in a .h file and the functions themselves in a .c file? Then you just need an additional #include directive, and an adjustment to the make file.

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

[leon de boer]

You are not thinking like a programmer ... at the moment your answers are not needed as you just display them to the console So one easy option to patch your code in Calculation.CPP is this

void input_Area(void) // ** Pt1 here you declare you are going to return nothing AKA a void
{
float width = 0, length = 0, answer = 0;
cout << "Enter the width of rectangle :";
cin >> width;
cout << "Enter the length of rectangle :";
cin >> length;
answer = rectangleArea(width, length);
cout << "The area of Rectangle is : " << answer << endl;
}

That matches your .H header file you don't have to change anything

#ifndef _CALCULATION_H
#define _CALCULATION_H

void input_Func(void); //Input function of text.
void input_Area(void); //Input function of Area. **** FIXED NOW MATCHES THE .CPP file
void input_Trap(void); //Input function of Trapezoid. *** STILL BUGGED .CPP says it returns a float this says void
float rectangle_Area (float , float); //Declaration for Rectangle Area.
float trapezoid_Area (float , float, float); //Declaration for Trapezoid Area.

#endif

So you could go and fix input_Trap in the same way I am leaving that as an exercise .. problem fixed. So there is another alternative which is to return the answer in Calculation.cpp

float input_Area(void) // ** Pt1 here you declare you are going to return a float
{
float width = 0, length = 0, answer = 0;
cout << "Enter the width of rectangle :";
cin >> width;
cout << "Enter the length of rectangle :";
cin >> length;
answer = rectangleArea(width, length);
cout << "The area of Rectangle is : " << answer << endl;

return (answer); // * So return the answer like you said you would at Pt1
}

Now you need to fix the header file Calculation.H

#ifndef _CALCULATION_H
#define _CALCULATION_H

void input_Func(void); //Input function of text.
float input_Area(void); //Input function of Area. **** FIXED NOW MATCHES THE .CPP file above
void input_Trap(void); //Input function of Trapezoid. *** STILL BUGGED .CPP says it returns a float this still says void
float rectangle_Area (float , float); //Declaration for Rectangle Area.
float trapezoid_Area (float , float, float); //Declaration for Trapezoid Area.

#endif

So you could go and fix input_Trap in the same way I am leaving that as an exercise .. problem fixed again. Look carefully at both answers all that changed is whether you return answer or not. In both cases the .H f

[leon de boer]

Your code is not in a fit state to put in modules .. however I have provided code that does roughly what you want in modules. The code includes error checks on the entry you don't do in any way. File: Calculation.H

#ifndef _CALCULATION_H
#define _CALCULATION_H

float RectangleArea (float width, float length);
float TrapezoidArea (float base1, float base2, float height);

#endif

File: Calculation.CPP

#include "Calculation.h"

//Calculation of Rectangle Area.
float RectangleArea(float width, float length)
{
float Area_Rectange;
Area_Rectange = width * length;
return (Area_Rectange);
}

//Calculation of Trapezoid Area.
float TrapezoidArea(float base1, float base2, float height)
{
float Area_Trapezoid;
Area_Trapezoid = height * (base1 + base2) / 2;
return (Area_Trapezoid);
}

File: Input.H

#ifndef _INPUT_H
#define _INPUT_H

/* Asks user for menu choice up to given max value */
unsigned int MenuInput (char* prompt, unsigned int maxNum);

/* Asks user for a float within given range, with prompt text */
float GetFloatInput(char* prompt, float min, float max);

#endif

File: Input.CPP

#include #include "input.h"

/* Asks user for menu choice up to given max value */
unsigned int MenuInput(char* prompt, unsigned int maxNum) {
bool validFlag = false;
unsigned int iResult;
do {
printf(prompt); // Put prompt on screen
int err = scanf_s("%u", &iResult); // Scan for a unsigned int and hold any error
if ((err == 0) || (iResult > maxNum)) { // Check value between 0 .. maxNum
printf("Invalid menu choice try again\n"); // If value is invalid .. prompt that
} else validFlag = true; // Value is valid
scanf_s("%*[^\n]"); // Make sure we dump any characters in buffer
} while (validFlag == false); // Loop until valid
return (iResult); // Return result
}

/* Asks user for a float within given range, with prompt text */
float GetFloatInput (char* prompt, float min, float max) {
int err;
float fResult;
do {
printf(prompt); // Put prompt on screen
err = scanf_s("%f", &fResult); // Scan for a float and hold any error
if (err == 0) { // Err = zero means entry is not a float
printf("Entry is not a float try again\n"); // Prompt entry was not a float to screen
} else {
if (fResult < min) { // Check entry is above minimum
printf("Re-enter value below minimum of %f\n", min);// Prompt

[Hassan Syed1]

even your code giving error. Have a look at screenshot please. However, Thank you for showing me the correct way to code. I got many point out of it. Screen Shot of Error = http://i64.tinypic.com/16m0zr4.jpg

[leon de boer]

Something funky with GCC compiler but easy to fix include float.h ... its doesn't know what FLT_EPSILON, FLT_MAX are. These are standard C++ Macro constant definitions so you can just look it up (float.h) - C++ Reference[^] So top of Source.CPP becomes

#include
#include // Added to define FLT_EPSILON & FLT_MAX
#include "calculation.h"
#include "input.h"
using namespace std;

In vino veritas

[Hassan Syed1]

More errors :( Thank you for your guidence at least i am learning new things. Screen Shot = http://i65.tinypic.com/ncjddc.jpg[^]

[leon de boer]

That one is you ... It is basically telling you it can't find the code for GetFloatInput. GetFloatInput is defined in Input.H and Input.CPP which are included see here

#include
#include "calculation.h"
#include "input.h" // <----- GetFloatInput is defined in this include>
using namespace std;

So we are down to either a typo error or you haven't included Input.CPP into your source files. I assume you cut and paste so unlikely to be a typo so lets try number two. Did you use the menu system and do .... Project... Add files... to add the new .H and .CPP to your source files to the project? I don't use code blocks but it will be something like that. Can I ask you to show me the line about the deprecated string function points to .. I am interested to see what GCC is complaining about. There is possibly another warning you are going to get on the definition of main in Source.CPP can you change it from int main() to

int main(int argc, char**argv)

That is the technically correct definition, not the Microsoft shorthand I used.

In vino veritas

[Hassan Syed1]

Excellent. Working fine now however I have to remove scanef_s. that _s was creating problem so i only remove _S and scanef remain as it. Now code working fine. Thank you for ur guidance. Now i got the clear idea how to write the code. I will copy the way you wrote this code. I am not a bad student however I like programming but problem is I think i am unable to think like a programmer. I am trying hard for that but no success yet :( I want to excel in this field but sometimes I stuck :((

[leon de boer]

We all get stuck at times :-) It is really pleasing to see you are willing to apply yourself to learn. None of us are born able to think like a programmer it is like any profession something you get good at by application of lots of time and effort. Your long single file code is sort of normal basic student level code, it works in a fashion. You are now seeking to move beyond that and I can only encourage that. All I did was really shorten up your code by making functions with more parameters and putting in error checking for things like typing letters instead of numbers etc. There are improvements you could do by using objects or classes but that is more stuff you are yet to learn. I looked up the problem with scanf_s it is they have changed security with this, you now need to use "%hu" rather than "%u" as meaning a pointer to an unsigned short. That tells you how many years since I have written code for a console application :-) So there are two fixes to remove the warning correctly

unsigned short iResult; // Define iResult as unsigned short not unsigned int

int err = scanf_s("%hu", &iResult); // Use %hu this should be error free on GCC

In vino veritas

[Hassan Syed1]

You are right. i am completely new and it was my class assignment number 1. I finsihed it and submitted it already but then I came to know professionals never write everything in main that's why i decided to search in this direction. By your improved code I can see a boundery wall is set for wrong inputs. Which i wanted to set in my project as well but was not sure how to set those powerful boundaries as you set. I want to excel in this game of programming, I am not an extera ordinary student but i will keep on trying it day by day :) Following are few things I extracted from ur code which I am going to follow for the next time code or will at least try my best to do similar things. Correct me if I observed wrong. I did not follow the following things in my code. If I missed any point then point me that as well. 1) You are using braces by giving one space and starting 1st curly brace in-front of the statements like while and if. 2) All variable you wrote in small letters and to make them more clear u out _ sign to link them. 3) Function name 1st character and then the 2nd meaning name of function is capital. 3) 1 step indentation on each step involving in some kind of computation. 4) You used unsigned when you feel that value are in +ve.

[leon de boer]

correct on all counts, you have correctly identified that the standard makes the code much more easily readable and helps you identify errors. I enforce the standards at our company and I therefore never write without using that standard. The standard we use is essentially an extension of C99 or sometimes called ANSI-C standard and is used heavily in the sector I work, which is embedded programming. Companies in the game market you are looking at tend to use C++ (UNREAL GAME ENGINE etc) or C# (UNITY GAME ENGINE) and there standard may differ slightly as the majority of the code won't be C compliant, and they have other pressures for readability. So generally in large companies you will be expected to write to a standard and there will usually be a process to check code into the active repository. So while learning coding try and have your own standard but just remember you may have to adapt when you are employed. The company is not going to rewrite an entire repository to your standard even if you could argue it was better. So my standard is not the "absolute best" it's just a standard I would generally have to write to at work.

In vino veritas