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?
View 8 RepliesI am getting undefined references when compiling a project, however, there in no reference to external library and I am including all source file and header in the project , beside the only reference is to standard C header files. The undefined references error I am getting is for a header file whose source file is already present in the project.
View 6 Replies View RelatedI was working on template and found the linker error while compiling the code.
Below is the code:
Code: //Template1.h: Header file where template define
#ifndef __Template1_H__
#define __Template1__
template <typename T,typename T1> class A
{
T a;
T1 b;
public:
A(T ,T1 ) ;
[code].....
In a part of my code I'm defining limits over a variable which is in type of:
fftw_complex *i_phi
Then it is initialized as:
i_phi = (fftw_complex*) fftw_malloc(nx*ny* sizeof(fftw_complex));
The limits are defined as follows.
if ( creal(phi[i]) < 0.0 ) i_phi [i] = 0.0;
if ( creal(phi[i]) > 1.0) i_phi [i] = 1.0;
}
[Code]....
Printed numbers are showing a lot of fluctuation around limits eg, 1.00542, 1.0002 and -2.45829e-12.
I really have no idea why the limits are not applied for a lot of cells but my guess is that it's a problem from the CREAL function. Also I've changed the CREAL with __REAL__ but still the same problem shows up.
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?
how to remove the linker error as mentioned above..
i have created a simple program in C++ as given below
#include<iostream.h>
#include<conio.h>
void add(int a,int b);
[Code]....
i saved it with name PIYUSHAN.cpp.after compiling above program, it shows no errors, that means it get compiled successfully. but when I try to run this program it shows Linker error :
Undefined symbol add(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol sub(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol mul(int,int) in module PIYUSHAN.CPP
Linker error : Undefined symbol div(int,int) in module PIYUSHAN.CPP
I have this code in my project
Code:
// OpenGL1.cpp : main project file.
// #include "stdafx.h"
#include "windows.h"
#include <GL/gl.h>
[Code] ....
and I got this error:
Configuration: Debug Win32 ------
1> OpenGL1.cpp
1>LINK : fatal error LNK1104: cannot open file 'C:Program FilesMicrosoft SDKsWindowsv7.0AIncludegl.obj'
Why it wants the gl.obj and how to make this code working without error?
We have a midi.cpp which includes midi_synth.h.
this h file declares a class and this class inlines a open method.
Now the linker doesn't recognize this open method when called by another method inside midi.cpp.
What would I do?
Define a constant PI that has a value of 3.14159
- Create a double variable, Radius with an initial value of 10
- Create two double variables. Circum and Area, without initialization
- Using the following formulas, compute circumference and area of the circle:
circumference = pi * r * 2 (here, r means radius)
area = pi * r * r
- Display the result using three variables (numbers must come from variables)
- Expected output: (Don’t forget to display the period at the end of the first line)
Circle with radius of 10.
Circumference = 62.8318 Area = 314.159
The question is: Define the class Counter. An instance of this class is used to count things, but the counter should never be less than 0 (non negative number). The member variable should be private. I realize what I'm suppose to be using but can't implement the member functions needed..
int main(){
int value;
cin >> value;
Counter myCounter(value);
for (int i = 1; i <= MAXLOOP; i++) {
myCounter.increment();
[Code] ....
#include <graphics.h>
#include <stdio.h>
#include <conio.h>
#include <math.h>
void main() {
int gd = DETECT, gm = DETECT, s, dx, dy, m, x1, y1, x2, y2;
float xi, yi, x, y;
[Code] ....
i've defined an strcuct in .h file and i read its variable in a method in .cpp file ,but i'v got error.
.H file:
class myclass{
public:
struct opt_struct
[Code]....
when i declare the struct without static , it doesn't recognize my struct and with static i face linker error:
Error33error LNK1120: 1 unresolved externals
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] ....
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.
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;
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;
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?
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].....
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]....
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());
}
}
//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] ....
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...
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.
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] ....
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]....
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();
}