C++ :: modifying Several Variables Via Header File
Feb 18, 2014
I'm trying to split up my game (about 1300 lines) into header files, but I'm coming up with a problem whenever I try and put a function in a header file, when that function was modifying some variables that were defined before int main in the .cpp. For example:
int variable1 (0);
int variable2 (0);
void increasevariables() {
variable 1 = variable1 + 1;
variable2 = variable2 + 1;
[code].....
If it only modified one variable then I could just pass that variable and the return it:(return variable1 + 1;)But I don't know how to make a function in a header file modify several pre-existing variables. In the actual program, the variables are dependant on each other and the modifying is a lot more complicated, so I'd rather not split it into several functions and run one at a time if there's another way.
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Feb 24, 2014
I declared 3 private variables in header file.
I try to access one of the variable in its corresponding cpp file but I get an error message saying it's undefined. I did #include the header file. Why is this?
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Apr 12, 2013
I just can't seem to find how to create a header file and where I can change the value of the variables. It sounds simple.
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Oct 15, 2013
I read in another forum that it is bad practice to declare static variables in a header file? Is that true and if so why.
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Mar 10, 2013
I need to write a C++ program, that extracts certain variables, x y z, from a file that is continuously being updated x y z. These variables are going to be used to recalculate a new answer.
My question is to see if it is possible to have an include .h file that is always being updated so that I can extract these three variables from it, and always have the newest venison of each variable, so that the answer to the equation is always the newest updated. Should I use fopen or fwrite to do this.
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Jul 10, 2014
I am trying to modify a user control while modifying the main form. For example i have my main form open in one visual c# window and my user controls in another. However it seems that in order for my code changes in my user control to have any effect on the main form i need to close all my c# windows and then re-open them and even then that sometimes doesn't work am i doing anything wrong or is this supposed to happen??
Also yes i am saving and clicking build solution on my user controls.
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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 28, 2014
How would I change the private variables in the header files and the code in the cpp files for the primary indexes so they use a dynamic array or vector instead. For the primary index, the initial vector size will be 8.
header
#ifndef MY_PRIMARY_INDEX_H
#define MY_PRIMARY_INDEX_H
#include
#include
#include
#include
class PrimaryIndex
[Code] ....
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Feb 10, 2013
I have written my program and it works when I keep everything in the header files, and then have my main. I am now splitting them up into implementation files, but Eclipse keeps giving me errors. It gives me error at every opening brace of the constructor and functions. It says on all of them "Redefinition of (name of constructor or method), Previously declared here." What am I doing wrong, because it works in the header file?
#include "KeyValuePair.h"
template<typename Key,typename Value>
KeyValuePair<Key,Value>::KeyValuePair()
[Code] .....
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Apr 12, 2014
I am working on an assignment in which i have to perform th following task
myClass itsObject1,itsObject2;
itsObject2=5000+itsObject1;
I have defined overloaded operator as follows in the header file but in the cpp file of the class it gives error.
friend vli &vli::operator + (int &a,vli &obj);
How to define it in cpp file of my class?
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Sep 12, 2014
What is the right syntax for implementing the .cpp of a template class?
Consider this LinkedList.h file:
Code: #include<iostream>
#include"Iterator.h"
template <class T>
class LinkedList {
[Code] ....
How should the implementation for the LinkedList constructor, for example, should look like in the LinkedList.cpp file?
I tried this:
Code: #include "LinkedList.h"
template <class T>
LinkedList<T>::LinkedList<T>() {
// constructor
}
LinkedList<T>::~LinkedList<T>() {
// destructor
}
But the compiler wouldn't accept it.
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Jan 17, 2015
lets say we have a valid class with full implementation, X. can this class be declared as forward in Y header file:
Code: class X;
class Y{
X* m_X;
}
but still be used as regular in the cpp file?
Code:
#include "Y.h"
#incldue "X.h"
T Y::function(){
m_X->doSomething();
}
visual studio prevents me from doing it , I wonder if the standard also says so.
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Dec 11, 2014
I wanted to share the value of a variable from Sender Program to Receive after program and want to calculate difference between send and receive. After studying Header file concept I program following three.
Now I am struck. How to to compile? I link all these file. I used following method:
Code:
gcc Sender.c -o Sender Sender.h
gcc Receiver.c -o Receiver Student.h
Then I run Sender and after that Receiver.I per my knowledge, Receiver should give difference but it gives error :
Code:
Receiver.c: In function "main":
Receiver.c:10:42: error: "Send" undeclared (first use in this function)
printf(" Total Receive is %d
",Receive-Send);
Code:
Sender.c
#include <stdio.h>
int Send ;
void main(){
[Code] ....
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May 21, 2014
I have been working a project in C++. I have TTTMain.cpp file that has all the function calls, TTTFuntions.cpp that has all the functions, I have TTT.h file that has all the prototypes and variables and additionally I have Winner.h that has enum class Winner declaration in it. Here is my block of codes:
Winner.h file:
#ifndef winner
#define winner
enum class Winner {
[Code]....
My question is when I compile this gives me error on
Winner gameSquares[] = { Empty, Empty,Empty, Empty, Empty, Empty, Empty, Empty, Empty };
with saying "invalid use of non-static data data member" and It says "Empty was not declared in this scope."
I know calling enum is very very trick.
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Mar 7, 2014
I am new to C++ and am trying to modify an array inside of a function.
It is of my understanding that you cannot return an array from a function?
Would writing it to a data file and then retrieving it be a solution to this problem?
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May 8, 2014
I have a class that loads the contents of a XML file into their respective object types and stores those objects in a list. Each object has its own list of objects with properties the program will later modify.
The problem I am currently having is that after looping through the objects and modifying the necessary properties the modifications do not persist. This leads me to believe I am modifying a copy of the object rather than the object I think I am modifying. I am not sure why this is happening as I believe I should be modifying the object that is referenced in the collection.
What I have tried, I started using LINQ to get the object I am looking to modify. After a little more research I don't think this can work properly due to the LINQ query returning a new object(copy of the object). Currently I am using nested foreach loops which still are not behaving the way I expect as the properties I am setting are not making their way back to the original object.
The PopulateLogSheet() in the following class is where the problem loop is.
class ChillerCheckCollection {
public List<Chiller> chillers = new List<Chiller>();
public void LoadChillers(string filePath) {
var availableChillers = (from chiller in Xdocument.Load(filePath).Descendants("chiller")
select new Chiller
[Code] ....
And here are the other classes referenced in the above class.
class Chiller {
public IEnumerable<LogSheet> chillerLogSheet = new List<LogSheet>();
public int chillerID;
[Code] ....
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Nov 19, 2014
Here is the problem:
Write an algorithm such that if an element in an M * M matrix is 0, its entire row and column is set to 0.
Your function prototype may look like the following:
void setZeros ( int size, int arr[][size] );
Heres what I have:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 3
void scan_matrix(int arr[][SIZE]);
void print_matrix(int arr[][SIZE]);
void initiailize_matrix(int arr[][SIZE]);
void set_zeros(int matrix[][SIZE]);
[code]....
I'm not sure on how to scan zero for this code and I have bolded some comments that I am having trouble with as well.
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Mar 26, 2013
I have an array of char representing pixels in a bitmap, which I want to modify. I don't think I can just iterate over the array and pass chars into a function individually, because the function needs to take into account the neighboring pixels, too.
I thought of two ways to do this. The first would be to pass the array to the function as an argument, then have the function change it and return it. The trouble is I'm not exactly sure what happens internally when you pass an array to a function and return it. Is it the same array, modified? Or is it a copy of the array, so now you're using twice as much memory?
Alternatively I guess I could have a function with a void return type and pass a pointer to the array. I'm somewhat new to this, but the way I understand it is that a pointer is like the address of a house, while the array is the actual house. So if I give the function the address, it can go to that address and rearrange the furniture inside the house. Then, after the function returns, I can go to that address myself and see all the rearranged furniture, even though the function has already returned.
Is there a problem with the second way? It seems a bit neater, but maybe I'm understanding pointers wrong.
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Jun 21, 2014
I have to read a particular student data from file using his Roll no and modify it and then save it to file again
This is the File
24 salman 98 97 96 95 94 A ;
21 faizan 88 87 86 83 85 B ;
35 Gohar 99 98 97 96 90 B ;
45 sibghat 91 92 78 85 88 C ;
009 john 89 87 91 78 95 C ;
how can i read data of roll no 35 and modify it and save it again to the file
this is my program
int r = 0 ;
while ( ar[j]!="0" ) {
//cout << "Salman majid is
" ;
if ( ar[j]==k ) {
r = j ;
getdata() ;
[Code] .....
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Jun 20, 2014
I would like to understand how to rotate a 3D Object around it's Center, by modifying it's Vertex Coordinates. N
The reason is that I need to keep track of the new coordinates because of my collision system, which is based on Vertex Coords.
Here is the Code for an Object
void DrawHouse(GLfloat x1, GLfloat x2, GLfloat y1, GLfloat y2,
GLfloat z1,GLfloat z2, GLfloat u1, GLfloat u2, GLfloat v1, GLfloat v2, GLuint textid) {
glBindTexture(GL_TEXTURE_2D, textid);
glBegin(GL_TRIANGLES);
glNormal3f( 0.0f, 0.0f, 1.0f);
glTexCoord2f(u1,v1); glVertex3f(x1,y1,z2);
[code]....
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Nov 22, 2012
I've got
[tranlated]
Code:
error C1083: cannot open: '[!output PROJECT_NAME].h': No such file or directoryd:program files (x86)autodesk3ds max
2012maxsdkhowto3dsmaxpluginwizard emplates1033atmospheric_type_atmospheric.cpp1513dsmaxPluginWizard
I opened the project
Changed it to vc100
Changed it to x64
Disabled optimization
And compiled
And the results are shown above
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Jul 29, 2013
I am beginner in c++ language. i'm use visual studio 2010 ultimate. the problem is i can't add c++ file(.cpp) and header file(.h).
Here the screenshot : [URL] ....
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Dec 27, 2014
I made my header file. If cpp file with definitions is in project compiler knows it has to be linked, but if it's not compiler doesn't know. If I include standard library or boost I don't have to manually link cpps. How to do so including my header automatically links cpp? Maybe problem is with something else?I use VS 2013.
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Jan 30, 2013
My socket.cpp program got error. it showed "socket.h: no such file or directory". I had put my header file (socket.h) in the same place with my source file.
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May 23, 2013
My code is currently reads in a string of lower case letters, identifying the occurrence of each letter.
Code:
#include <stdio.h>
#include <string.h>
int main()
{
[Code]....
My issue is that I want my code to read uppercase and special symbols. showing the occurrence of both.
Code:
else if(str[x] >= 'a' && str[x] <= 'z');
else if(str[x] >= '0' && str[x] <= '9');
However I struggle to implement it
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Feb 27, 2015
I am having trouble modifying a linked list. I am writing a function to delete the last node from the linked list, but it gave me incompatible types error.Here is my struct:
Code:
typedef struct PCB{
int id;
struct PCB *next;
struct PCB *prev;
}PCB_rec, *PCB_p;
Here is my function to delete the last node (given the pointer is pointing at the last node of the list):
Code:
void del_last_node(PCB_p *process_list){
PCB_p temp = process_list;
if (temp->prev != NULL){
temp = temp->prev;
[Code] ....
And here is how I called the function:
Code: del_last_node(&process_list);
It gives me the following errors:
initialization from incompatible pointer type at line:
PCB_p temp = process_list
assignment from incompatible pointer type at line:
process_list = temp
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