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.
How I can implement it.
Tickable.h
#include <list>
#ifdef TICKABLE_EXPORTS //Automatically defined by MSVS
#define DLL __declspec(dllexport)
#else
#define DLL __declspec(dllimport)
#pragma comment(lib, "Tickable.lib")
#endif
class DLL Tickable{
[Code] ....
error LNK2001:
unresolved external symbol "private: static class std::list<class Tickable*,SKIPPED BITS> Tickable::subs" HUGE_SYMBOL_LIST
PATHTickable.obj
I know with such a tiny and insignificant class the dll export seems pointless but this class is actually intended to be a .lib ONLY. But it is derived from by .dll style classes, and through inheritance this error is the exact same as what appears in the derived class, I just imagine that the cut down version would be easier to work with.
Is it possible to hold either a static variable in a dll which is of a dynamic type, OR would it be possible to reference an external variable which is static throughout the instances and this variable can be chucked away in a namespace of mine somewhere?
I suppose my only other option (if this is possible) would be to define a maximum instance number and create a standard array of pointers but this could both waste so much memory when not in use and cause problems if I need more memory.
How do I insert a array size as variable?
View 5 Replies View RelatedThe WinAPI has a struct like this for raw input:
Code:
typedef struct tagRAWINPUT { RAWINPUTHEADER header;
union {
RAWMOUSE mouse;
RAWKEYBOARD keyboard;
RAWHID hid;
} data;
[code]...
The definition of the struct doesn't show it but the documentation says that bRawData is variable length. sizeof(RAWINPUT) will not be the correct size when the data field is of RAWHID type so how do you allocate a variable with automatic storage type that has the right size for the entire struct? You can get a header that has the size for the entire struct but how do you actually allocate storage space for the data without using malloc? I've seen some example code that used a char array but that violates aliasing rules and there are also alignment issues with that approach.
I am wondering how I could make an array which contains arrays, but with a variable size.My first try..
Code:
int array[][] = {{1}, {2}};
But this isn't proper
I have a function like this
void foo( int i) {
...
uint8_t buf[ i];
...
}
And I don't understand why the compiler is not complaining... I'm using g++ -c -g -Wall to compile ....
I am new to C. I've been trying to use C to code some statistical functions originally coded in R. I've encountered an interesting phenomenon. In the function foo1, I declared the array v1v2b using an actual value 1999000. The function runs fine when I call it in R.
Code:
void foo1(double *x, double *y, int *nsamp){
int i, j, k, oper=2, l;
double* v1v2=malloc(sizeof(double)*((*nsamp)*(*nsamp-1)/2 + 1));
outer_pos(x, y, nsamp, &v1v2[0]);
double v1v2b[1999000]; //<-------HERE
for(i=1; i<= 1999000]; i++){
v1v2b[i-1]=1;
} }
However, in foo2, I first create an integer variable called index, and store the value 1999000 in it. I then use it to initialize the same array. When I tried calling this function in R, it either led to a stack overflow error, or completely crashed R.
Code:
void foo2(double *x, double *y, int *nsamp){
int i, j, k, oper=2, l;
double* v1v2=malloc(sizeof(double)*((*nsamp)*(*nsamp-1)/2 + 1));
[Code] .....
I am having following pointer variable declaration
Code: Static double (*funcs[]) (double) = { sin,cos,tan,asin,acos};
Here funcs is an array of pointers to functions which take double as input and gives double as output with static as storage type am I right.
For my default constructor I need to set an array of strings to null and the size variable to 0. Here is my code for that
DynamicStringArray::DynamicStringArray() {
*DynamicArray[]=NULL;
size=0;
}
When I try and compile it I get an "expected primary expression before ']' token" error.
So i'm creating bank system. Where I have function that reads the text file (balance), and I make a deposit, which adds what was in the balance = deposit + balance.
But this is what is happening. In my text file i have number 10. Function balance works fine and reads 10 from the text file.
When I make a deposit add a value to the balance, if i add 7, the new balance is 17. And i check the text file shows me is 17. Which is correct.
The problem is here. If i make another deposit, without closing the program, for example i add 5 to the balance, the new balance should be 22 = 17(balance) + 5(deposit), because 17 was store on the text file and it was the balance that was store on the text file on the last time. But it shows me 15, it adds the balance that the program first started which was 10(balance) + 5(deposit), but should had had be 17 + 5.
When I close the program the value on the text file, is 15, that was the last sum that i did.
int main()
{
double balance = 0;
balance = currentBalance(balance);
menu(balance);
[Code].....
I've been working on making a class that makes turning any variable or object into a byte array and vice-versa, quick with minimal pointer interface.
As well as a function for turning any variable or object into a binary text string.
Code:
#include <iostream>
#include <bitset>
#include <sstream>
// Convert a Variable to a Byte Array
template <class var>
unsigned char* VarToBytes(var &data) {
[code].....
how to insert a variable for the size of array and prompt user to insert the elements for the array?
View 13 Replies View RelatedI'm doing a bitwise operations on 2 bytes in a buffer, then storing the result in a variable. However, I sometimes get a non-zero value for the variable even though I'm expecting a zero value. The relevant portion of the code is as follows.
Code:
unsigned int result = 0;
long j = 0, length;
unsigned char *data;
data = (unsigned char *)malloc(sizeof(unsigned char)*800000);
[Code] ....
I'm expecting result to be zero when my data[j] and data[j+1] are 0xb6 and 0xab respectively, which is the case for most of the time. However, for certain values of j, my result is strangely not zero.
Code:
j = 62910, result = 64
j = 78670, result = 64
j = 100594, result = 64
j = 165658, result = 512
j = 247990, result = 128
j = 268330, result = 512
j = 326754, result = 1
j = 415874, result = 256
j = 456654, result = 1024
j = 477366, result = 512
It appears that these strange result values are all powers of 2, with a 1 bit appearing somewhere in the unsigned int.
I'm not changing the value of result anywhere else in the code, and when I print out
Code: (unsigned int)(((data[j]^0xb6)<<8)|(data[j+1]^0xab))
I get 0, but somehow when it gets stored in result, it's no longer zero. I really don't understand what could be wrong.
I would like to create a table but I dont know how big. Thats why I want to use variable to describe its size. Something like that:
int x = 5; //I will use a function to set x
int Table[x];
What should I do to make it work?
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've been trying to store the inital size of a list in an int variable, so I can access it later in case I modify the list size. For example, I did the following:
std::list<AType *> myList;
myList.push_back(anATypeobject);
int initListSize = myList.size(); //initial list size
myList.push_back(anotherATypeobject);
myList.push_back(yetanotherATypeobject);
while(myList.size > initListSize)
myList.pop_back();
What this is supposed to do is to get an initial size of a list, and then be able to return to that initial size. However, when I try to do it in my code, initListSize always change if myList.size() changes. Is there a way to change that?
I would like to convert a float or double variable into unsigned char variable and back.
float number_float = 23.453f;
unsigned char* number_char = (unsigned char*)malloc(sizeof(float));
number_char = reinterpret_cast<unsigned char*> (&number_float);
float* number_float_0 = reinterpret_cast<float*>(&number_char);
I am not getting the same value back.. why?
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
I have to write a loop assigning a variable x to all positions of a string variable and I'm stuck. I don't have extensive experience with arrays and I'm also a bit confused about C-String. The problem is below.
"Given the following declaration and initialization of the string variable, write a loop to assign 'X' to all positions of this string variable, keeping the length the same.
char our_string[15] = "Hi there!";
(Please note this is a 'C-string', not C++ standard string.)"
I have an example where I have a variable belonging to a base class, but I would like to tell the compiler that it actually belongs to a derived class. How can I do this?
// base class: R0
// derived class: R1
// see function SetR1 for the problem
class R0 {
public:
int a;
[Code] .....
I am trying to access a variable from another class through another class but it is not returning its "instance"?
Example:
Class View
Code:
...
V3D_Viewer viewer;
...
Class MainWindow
Code:
...
viewer* myView;
myView = new viewer();
...
Class Test
Code:
...
MainWindow window;
window.myView->setBackgroundColor(WHITE);
...
I am new to c++ references and pointers,
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?
I want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like
struct item {
int ID;
int special; // for function
};
item Key;
Key.special = UseKey(KEY_KING);
// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this
if(iCurrRoom == ROOM_KING)
Key.special;
else if(iCurrRoom == ROOM_DRAGON)
Fireball.special;
Here is the link for my program, I want to access the average value which is located in grade.c (calculate_grade) class through driver.c (main function) but I don't know how to make "average" visible
[URL] .....
#include<iostream>
#include<conio.h>
#include<string>
using namespace std;
class ir;
class Bank_acc {
private:
string name,type,s;
long int accno,temp,balance,in;
[Code]....
errors are:
|6|error: forward declaration of 'class ir'|
|54|error: invalid use of incomplete type 'class ir'|
|99|error: no matching function for call to 'ir::interest()'|
how can I make the queue of type pcb
and how to access pid in other clases?