C++ :: Creating Global Variable / Pointers?

Jan 6, 2012

I am making two classes using the juce library [URL] ....

this is a problem that has now come up after solving an earlier problem i posted but its a completely seperate issue.

i have a class for loading a file when i button is clicked that seems to work. Here is the function in my LoadButton cpp:

void LoadButton::buttonClicked(Button* button)
{
FileChooser pedoFileChooser ("Choose an Audio File", File::nonexistent, String::empty, true);
if (pedoFileChooser.browseForFileToOpen())
{
File pedoFile (pedoFileChooser.getResult());
}
}

I want to be able to then use the file stored in pedoFile in the cpp of another class called PlayButton. I tried doing this with a pointer? not sure if that's correct way of doing it (i know very little about C++ or programming) by changing the function to this. I'm getting the error invalid initialisation of non-const reference of type 'juce::File*&' from a temporary of type 'juce::File'

void LoadButton::buttonClicked(Button* button)
{
FileChooser pedoFileChooser ("Choose an Audio File", File::nonexistent, String::empty, true);
if (pedoFileChooser.browseForFileToOpen())
{
File* &pedoFile = (pedoFileChooser.getResult());
}
}

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C :: Transform Local Variable Into Global Variable?

Oct 25, 2014

I need to transform a local variable into a global variable so I can use it in one of my functions. I thought about passing the value as a parameter to this function but I can do this since the function is called inside the while loop and this variable counts how many times the while loop does (so the final value is outside the loop). Example to visualize better:

Code:
while(condition) {
function(parameter1, parameter2);
count = count + 1;
}
printf("%d
", count);

So, I need to transform the final value of "count" into a global variable. Can I do this?

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C :: Use Pointers Instead Of Global Variables?

Oct 15, 2014

I have made an application and I have basically solved everything. But the only problem is that I am using global variables because it felt like the smoothest, so my program is built on it.

But now I've read around and I understand that you should not use these(?). Do you think pointers is the best think to use instead?I have previously declared my board array and some variables as global and I want them in alot of functions.I have read and understand the procedure for the use of pointers so I can use my int's in the other functions by doing like this? Code: #include <stdio.h>

int justprint();
int main()
{
int Row = 2;
int Column = 2;
int *pRow = &Row;
int *pColumn = &Column;
[code]...

But how do I do it with an array like this one? If I declare it in the main function, and then want to use it in other functions.Or are there better, easier solutions?

Code: char game[3][3]={{0,0}};

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C++ :: Global Variable - Calling Sub Function

Dec 19, 2013

Expected output: 20

But what I got is: 22

Why. While calling sub function it should take the global variable am I right

insert Code:
#include <iostream>
using namespace std;
int a=0;
void sub()

[Code] ....

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C :: Global Variable - Only Printf Works

Apr 20, 2013

Okay so I am programming an 8051 variant to interact with an SD card. In a separate initialization routine in SD_CARD.c I pull out the vital information of the card into global variables. I then call Menu() which is in another source file but includes a header file with all of the variables declared as extern. Now here is the weird, part this is from my Menu.c

printf("%u" , VOLUME_1_SECTOR);
if(VOLUME_1_SECTOR==16384)
printf("Correct");
else
printf("Incorrect");

Now the output of the first printf is 16384 but the conditional evaluates to false. If I put this code in SD_CARD.c (Where VOLUME_1_SECTOR is defined) the conditional evaluates to true. I am confused why the printf works correctly in Menu.c but not the conditional.

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C :: How To Scanf Global Variable Outside The Main

Sep 7, 2013

The problem that I want to make an array " vertextDegree [nbColours] " with " nbColours " elements in it ,but the "nbColours" unknown and I have to get it get it from a file .

Code:

int nbEdges,nbVetices, nbColours ;
typedef struct st_graphVertex {
int index;
int colour;
int val ;
int vertexDegree[nbColours]; // it won't work because nbColours unknown
// here and I want get it from file in the main
struct st_graphVertex *next;
t_edgeList *out;
}t_grapheVertex;

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C++ :: Private Global Variable To Class?

Sep 30, 2014

I want to make a destructor counter...So it needs to be outside that specific instance of the class. And i want to keep it hidden. I don't want to be able to access it from outside the class...I Don't want main.cpp to have access to this variable

Is there a way to do this?

static int destructorCount;

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C++ :: Changing Global Variable In A Thread

Jul 28, 2013

I have a small problem with my program. It is kinda a mess but I will try to explain you what I am trying to do. I have some threads. One of it, it attempts to detect a game client. So my code is sort of like that:

DWORD ProcessID; // The process ID of the game client
void test() {
char* text;

[Code]....

So basically, its like the variable changes, but only inside the thread... why does that happen?

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C/C++ :: How To Declare Global Variable In Structure

Apr 28, 2015

I am getting this error while trying to compile my program:

It says that my variables "nome, cognome, eta..etc" are being used for the first time in my "inserisci" function.

I tought that I could just declare them as global in my structure like I did in my code, but apparently this doesn't work.

Do I really need to declare them again outside of my structure? Isn't there another way?

Here is my code:

#include <stdio.h>
#include "readline.h"
void inserisci(void);
struct impiegato{
char nome[20];
char cognome[20];
int eta;

[code].....

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C/C++ :: Global Variable Extern Typedef Int?

Oct 8, 2014

I have a .c file for each function of my program and i have .h,so how can I extern the following

in my main...

typedef int table[100][100];

how can I extern them in the .h and c files?

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#define HEIGHT 100
#define WIDTH 100

[code]....

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Visual C++ :: Global Variable Scope

Jun 15, 2014

//I dont understand this why does "<< "
The value of global now is: " << global << "
";" is equals to nine

#include <iostream>
int subtract (int a, int b);
int global = 5;
int main(void) {
using std::cout;
int a, b;

[Code] ....

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C++ :: Access Variable From Other Scope Without Global Declaration?

Aug 8, 2013

Code:
#include <iostream>
using namespace std;
void f() {
int x=17;
//cout<<main::y<<endl; i want to access y from main scope
}

int main() {
int y=23;
//cout<<f::x<<endl;

I want to access x from f scope is there any way for this without global declaration? specially about function scopes...

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C :: User Input Variable To Global Array

Oct 11, 2013

I am trying to create a global array with user-defined dimensions.the code is:

Code:

int matr_size()
{
int x = 0;
printf("Please enter the number of nodes: ");
scanf( "%d", &x);
printf("There are %d nodes in this simulation.", x);
getchar();
return x;
}

[code]....

I read that an array cannot be defined by a variable in C so I assume that is the issue, but I'm not sure how else to do it. Previously the size was defined by #define NODES and it worked fine but I need this user input.

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C/C++ :: Necessity Of Global Variable For Recursive Function

Nov 30, 2014

If I define the variable 'total', everything works well without any problem. But if I define it inside the function 'sum', I get irrelevant results, because each time the function gets executed, the variable total gets defined again, losing its value already assigned to it.

Do I have to use a global variable? Is there any way that I can do with without using a global variable?

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int total;
int sum(int a, int B)/>{
if (a < B)/>{
//printf("The total is %d, a is %d, and b is %d", total, a ,B)/>;
total += a;

[Code] ....

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C/C++ :: Use Global Variable Stored In File In 2 Different Functions?

Mar 13, 2014

Ok so when the program runs the first function the data is stored and displayed in the file. The second function is supposed to read the name entered, compare it to the ones in the file then take the price with it BUT I seem to have done something wrong when reading the files (or maybe it has to do with the global function I'm not sure). Here's parts of the code :

#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>

[Code]....

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C/C++ :: Create Local Instances Of A Global Variable?

Oct 4, 2012

is it possible to have a global variable pointing to a different address depending on the thread?

Imagine one would like to use threads with the loop:

for (i=0;i<n;i++){
globalPointerVariable=getAddress(i);
DoThingsUsingThe_globalPointerVariable();
}

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C++ :: Defining Global Variable - Linker Error

Jun 18, 2012

If I DEFINE a global variable in two source files which belong to the same project, then there is a linker error "multiply defined symbols". But if I DEFINE a global variable in two source files which belong to the different projects, then it compiles fine. Why?

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Nov 17, 2013

is there any variable type(or with another keyword) that we can change it's value in global scope?

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C++ :: Difference Between Static Local Variable And Static Global Variable?

Aug 5, 2013

Here is the code,

Code:
class A {
};
A& CreateObject() {
static A a;
return a;
} static A aa;
int main() {
return 0;
}

So is there any difference between a defined in CreateObject and aa?

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C++ :: Storing Variable Size Pointers Array As Class Variable

Mar 2, 2013

This problem is best explained by looking at its output below. I stored 15 different values but when retrieved some are wrong.

#include <iostream>
using namespace std;
class A {
public:
int ** pointer;

[Code] ....

I need to store and retrieve the 15 different values correctly. How to solve this? The main thing is, I need to store the pointer in class A objects.

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C :: Save Data From Global Variable Into Linked List

Jul 6, 2013

I'm trying to run so called student-administration program.I got functions that can read and write student data, but the one saving the data from about 30 students has some problem that I can't figure. (warning: I'm quite new to C programming)so this is the code:..I guess I can't use global variables as function arguments?

Code:

//global variables
static char ReturnName[31];
static char ReturnFirstName[31];
static float ReturnAverage;
}

[code]....

incompatible types when assigning to type 'char[31]' from type 'int'

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C :: String Declaration As Global / Main Local Variable

Nov 14, 2013

When a declare a string e.g.

Code:
char str[30]; as a global variable, the srting is initialized to NULL.

But if I declare char str1[30] INSIDE main(), then the string has garbage inside.... Why this happens??

E.g. the following code snippet...

Code:
#include <stdio.h>
char str[50];
int main(){
char str1[50];

[Code] ....

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Visual C++ :: Creating A Variable Using A Variable?

Jun 16, 2013

Any way to create a variable using a variable in the name? So E.g. if you wanted to create an int named nr(x), and x was 1, you would get an int variable named nr1? How would you do this?

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C/C++ :: Dynamically Creating Array Of Pointers?

Apr 6, 2014

I have a structure, containing a pointer as a member. I dynamically create an array of that structure type, and then need to dynamically create an array for its pointer member.

#include <iostream>
#include <string>
using namespace std;

[Code]....

There is more of my program afterwards, but it shouldn't matter. The errors I am getting at compile time are that I cannot convert an int pointer to an int (line 29) and that test is not a member of CourseGrade (lines 44/45).

My thought is I might be using the * operator incorrectly. My code before hand in line 29 was

for (i = 0; i < numberStudents; i++)
*studentPtr[i]->tests = new int[numberTests];

but the compiler suggested a '.' rather then the '->'

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C/C++ :: Creating A Temporary Vector Of Pointers?

Sep 10, 2014

Is it possible to create a temporary

std::list of pointers

I would like to pass a temporary

std::list

to the constructor of a class to initialize its own one.

For example, using a

std::vector
:
#include <iostream>
#include <vector>
void func(const std::vector<int*>& myVec) {
for(int i=0; i<myVec.size(); ++i){

[code]....

Can we do this? What are other possible problems in addition the ones I have just mentioned above?

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C++ :: Creating A Class Variable With A String?

May 12, 2013

I have defined a class in a header file; just the class, no templates involved. I have a program where I'm reading in data in string format. Each string consists of a word, a delimiter, and a variable name. Example:

cajun/mustard

I want to take that string and make it the variable name of that class type. It would be implemented along the lines of:

Code:
string str;
//read/process string here, get:
str = "mustard";
createName(str);
//pass string to creator function When the function is called, I should get the variable:
Class mustard;

Thing is, I'm not supposed to know beforehand what the variable names are, only that I create them as they are read in. It could be mustard, it could be Maynard_James_Keenan, it could even be bazinga.

My problem is, what do I do for createName()? I've looked into the concepts of pairing, Factory implementation, and maps, but I don't think they answer my question.

(P.S. if I run into the same variable name being read in twice, what steps can I take to make sure that a duplicate variable isn't created? Do I need to add in code, or does the compiler know to watch for multiple variables of the same name?)

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