C++ :: Using A Header File Across Multiple Files?
Aug 2, 2014
So say I create a header file which contains a list of structs, and I want to use these structs through out my source and some of my classes... how would I accomplish this?
When I try to do it via #include, I get re-definition errors, due to the nature of #pragma once. If I switch to #ifndef then I lack defenitions in files other than the source.
Is there a way to define things such as structs across multiple files, which doesn't lead to re-definition errors, and doesn't involve manually re-created all the structs for each file?
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Sep 16, 2013
When including a header file in stdafx.h, should that file still be included in the source file where it is actually used?
If it is included in both places, is the one in the source file ignored?
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Feb 9, 2013
I'll start with my code.
#ifndef H_cylinderType
#define H_cylinderType
class cylinderType {
public:
void getRadius(double radius);
void getHeight(double height);
[Code] .....
I have read the section in the book but I am still unsure on how to use 2 header files. In my cylinderType header file, am I wanting to include
#ifndef H_cylinderType
#define H_cylinderType
public:
void getRadius(double radius);
void getHeight(double height);
[Code] .....
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Jan 28, 2015
this is my main cpp file:
#include<iostream>
#include<conio.h>
#include "C:UsersAmitDesktopNew foldersum.h"
using namespace std;
int main() {
int a;
int b;
[Code]...
this is my 2nd cpp file add two number
#include<iostream>
#include "C:UsersAmitDesktopNew foldersum.h"
int sum(int x,int y) {
return(x+y);
}
this is my header file used in both cpp file
#ifndef SUM_H
#def SUM_H
int sum(int x,int y);
#endif
error i am getting in main cpp in devc++
[Linker error] undefined reference to `sum(int, int)'
[Linker error] undefined reference to `sum(int, int)'
in 2nd cpp file [Linker error] undefined reference to `WinMain@16' [/code]
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Jul 10, 2013
For example, I have the below files in a project called Calculate :
Source files : Calculate.cpp , Average.cpp (with out main)
Header files : Calculate.h , Average.h
I knew in general, we have to include Average.h to project header file Calculate.h to make it as part of project.
technical difference between adding header file (Average.h) to either project header file (Calculate.h) or project source file (Calculate.cpp) ?
I found no difference in an output. But, there must be technical difference.
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Dec 21, 2014
Right now, I have and application that opens a multi file dialog box. I want to take all of the files I highlight when the dialog box shows up and display a messsage box with the path and file names. This is what I have right now:
Code:
private: System::Void button1_Click_1(System::Object^ sender, System::EventArgs^ e) {
String^ folderName;
Stream^ myStream;
OpenFileDialog^ openFileDialog1 = gcnew OpenFileDialog;
openFileDialog1->Multiselect = true;
[Code] ....
Currently, it only shows the first file that I choose. I want to make it so that the message box shows all of the files that I select when the open file dialog shows up.
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Feb 13, 2013
how to structure my classes so that they all "wire together" and inherit the proper functions and data that I want them to. I want to have a Car.c and car.h which are "wired" with body.c/body.h, which in turn is wired with a frame.c/frame.h, wheel.c/wheel.h, and driver.c/driver.h.
Each part of the car holds some type of data, mostly ints: The car has a (total) mass and car_name. The body has a mass and color. The frame has a mass. The wheel(s) have a mass and force. [There will be 4 instances of wheel] The driver has a mass and driver_name. Each of these functionalities must come from their respective .c and .h files, and be amalgamated in the car.c and car.h (which should contain all the functionality of its parts). Then, in my main test program, I am to make an instance of car and hardcode in its values of: mass (which comes from the total mass of all of its parts, this is where i start to lose it.
How will I access its parts' masses in the test program?), color (a character array), current position (an integer), current velocity (an integer), and current acceleration (which comes from the total newton force of the 4 wheels, again this is where I start to get very confused). (Then in the test program I am to print out a simulation of this car over a period of 100 seconds, and show its position, velocity, and acceleration at each point (based on the mass, total newton force, and starting position). This part is of course a simple while loop, and is somewhat trivial.)
From what I understand, I will need to allocate memory for all of the data each class holds. Then, using function pointers, as well as #include "X.h" , I will need to somehow link up all of the classes together so that car has access to all of the parts' functions which set, for example, the newton force of each wheel.
We have learned a slight bit about structs, malloc, sizeof, and pointers, but I have not used them to link functionality or data from separate classes together.
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Jan 16, 2014
I am writing a piece of code that requires me to display the last 1000 lines from a multiple text files (log files). FYI, I am running on Linux and using g++.
I have a log file from which - if it contains more than 1000 lines, I need to display the last 1000 lines. However, the log file could get rotated. So, in case where the current log file contains less than 1000 lines, I have to go to older log file and display the remaining. For e.g., if log got rotated and new log file contains 20 lines, I have to display the 980 lines from old log file + 20 from current log files.
What is the best way to do this? Even an outline algorithm will work.
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Jul 15, 2013
I'm using multiple C++ files in one project for the first time. Both have need to include a protected (#ifndef) header file. However, when I do that, I get a multiple definition error.
From what I found from research, adding the word inline before the function fixes the error. Is this the right way to do this, and why does it work? Should I make a habbit of just declaring any function that might be used in two .cpp files as inline?
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Nov 2, 2013
I have a piece of code in C with header files included. I run it on Mac OS X Maverick with XCode 4.6.2 installed. GCC is also installed. Note that Command Line Tools in XCode are already installed.
When I compile it, the error I receive says something like this:
add.c:1:19: error: stdio.h: No such file or directory add.c:2:20: error: stdlib.h: No such file or directory add.c:3:20: error: unistd.h: No such file or directory
However when I run it on Ubuntu, it compiles without a problem.What to do?
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Dec 9, 2013
So I've been making a header file and put variables in their own namespace to avoid conflicts. My question is, do functions in the header file normally go in a namespace too, or should they just be named in a way which makes them unlikely to be accidentally copied?
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Apr 2, 2013
My teacher talks about header files just having definitions and not declerations. I am writing a program that has a .h file and a related .cpp file along with a main.cpp it would be nice to have the .cpp file associated with the .h file compiled into an object file that would than just be referenced when the .h file is included. Am I making any sense?
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Sep 17, 2013
I want to use two header files in my program. Here is exactly what I want to do.
-In the first header I have a binary tree and a structure.
-In the second file I have another functions that need to use the structure in the first header.
-I also want to use a function from the second header in the first.
-And finally I want to do actions with both headers in a "main.cpp" file that contains only int main() function.
How to include the headers in each other and in the main.cpp to be able to do the actions above?
I try to include the first header in the second one and the second one in the first header. Then I include both headers in the main.cpp file. But the compiler shows me many errors.
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May 2, 2013
I have two header files, A, B.
A.h
namespace test {
struct info
{
int a;
}
}
B.h
#include "A.h"
int main {
test::info.a = 10;
}
However, it has an error. I don't quite understand how to use namespace.
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Aug 27, 2013
I'm working with CGAL - Computational Geometry Algorithms Library, which is a library of geometry functions declared as several thousand header-only files. When I run a basic program (source code [URL] ) I get this output: [URL]
I have tried switching angle brackets to quotes. I have also started reading up on CMake.
Do I need to walk the dependency tree and add all of those files to my CMakeLists.txt? Or is there a way to tell the compiler to look in subdirectories?
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Nov 6, 2013
I have some header files with generic functions. And in one of them, I define TRUE and FALSE. Recently I started using another header file and it defined TRUE and FALSE as well. That caused GCC to throw an error, and not compile. In my case I can put #IFNDEF around the values so that if it is already defined they don't get defined again, but is there a better way to handle duplicate names? I assume the case would be the same for duplicated functions, how does that get handled?
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Mar 6, 2015
I have a problem with making header files in c, i get the code written only in main.c and then i have to create a files with extension .h and extension .c but how to do it.
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Dec 3, 2013
I'm having with header files, specifically to do with the string data type. The objects work perfectly when I put them inside the .cpp but when I set it to include the exact same code in a .h, I get a string of error messages.
class Topic
{
private:
string NInfo, SInfo, EInfo, WInfo, Name ;
bool Quest ;
[code]....
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May 27, 2013
I want to include turboc.h file for some project
where do i have to add this file for mac xcode?
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Jun 8, 2013
I'm working on trying to figure out constructors and header files. Can ya'll help me out with this? I'm sure my code looks like a mess as I tried to piece together different solutions I've found. There's also an attempted copy constructor and operator function. Basically my problem is my source file says there is no default constructor for my class type. Here's my header code:
#include <iostream>
#ifndef _car
#define _car
[Code].....
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Oct 30, 2014
I currently have a running program "game.cpp" that runs a game of tic tack toe. I want to split the working functions into header files so that game.cpp isn't so cluttered. I have created two header files "displayBoard.h" and "gamePlay.h" but they wont compile because the functions are looking for variables that haven't been declared. First, here's the working code.
#include "displayBoard.h"
#include <iostream>
#include <limits> //This is required to catch invalid user input
class ticTacToe //A class to contain all our functions {
[Code] .....
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Jul 30, 2014
I am having the issue of trying to call functions of a class through the header file.
Test.h
#ifndef TEST_H
#define TEST_H
class Test {
public:
void Hello();
[code]....
This code returns the error "undefined reference to 'Test::Hello()'"
All I am trying to do is call the Hello(); function in a seperate file.
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Oct 13, 2012
msdos is present on my computer but it cannot include the header files but when i check all files are present but they still cannot include????????
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Mar 16, 2012
Here is what I did,
Code:
// A.h
const int salary = 1000000;
// B.h
extern const int salary = 1000000;
But I still got multi-definition errors. How should I fix it?
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Oct 2, 2014
I'm a beginner with C and wonder how to include single header files (*.h) in to my project. I mean header files which are not included to the standard installation package.
I thought it would work if I just copy the newheader.h file in to library folder c:MinGWinclude, but it didn't work. Is there some kinf of GCC -command or procedure to add these single header files or how it should work?
All of those standard header files are working well and I don't have any problems with them.
Environment I'm using is MinGW+GCC+Win7.
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Mar 26, 2013
Modify program 3 by saving the header file on your memory stick and remove it from the Header section of the VC++ in the Solutions window.
Code:
#include<stdio.h>
#define pi 3.141592654
#define A (num) * (pi) * (Radius) /* a macro defines a math equation */
float spherevolume (float);
main() {
[Code] ....
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