So I was teaching my friend about pointers. While doing so, I noticed that the address of two identical structs are exactly back-to-back. struct Foo { int a; }; struct Bar { int b; }; Which allowed me to do this: Foo foo; foo.a = 100; Bar bar; bar.b = 100; Foo *pFoo = &foo; Bar *pBar = &bar; (pFoo+1)->a = 200; This overr...
I have the code as below. I have a abstract template class Foo and two subclasses (Foo1 and Foo2) which derive from instantiations of the template. I wish to use pointers in my program that can point to either objects of type Foo1 or Foo2, hence I created an interface IFoo. My problem is I'm not sure how to include functionB in the inte...
hi, char **r; r = (char **)malloc(10); the above allocation is enough?dont i need allocate for char *r through for loop?any can explain which one is right? ...
I need to insert pointers of classes (inherited from QObject) into a QList. I know that the following syntax can be used: .h QList<MyObject*> list; .cpp list.append(new MyObject("first", 1)); list.append(new MyObject("second", 2)); ... and then free memory: if(!list.isEmpty()) { qDeleteAll(list); list.clear(); } This sh...
I came across the following code recently: class Foo { public: void bar(); // .. other stuff }; void Foo::bar() { if(!this) { // .. do some stuff without accessing any data members return; } // .. do normal actions using data members } The code compiles because in C++ methods are just functions th...
I'd like to know at compile-time the range of values for a pointer type. limits.h only specifies maximums and minimums for pure number types. I don't wish to use hard-coded constants, and I prefer not to compute a max using sizeof(foo*). ...
I am using the cstdio (stdio.h) to read and write data from binary files. I have to use this library due to legacy code and it must be cross-platform compatible with Windows and Linux. I have a FILE* basefile_ which I use to read in the variables configLabelLength and configLabel, where configLabelLength tells me how much memory to alloc...
Good Evening (depending on where u are right now). I am a little confused with the stl stuff for sorted sets... I want to store pointers of a custom class in my set and I want them to be sorted by my own criterion and not just the pointer size. Anyone has an idea how to do this? Since it is impossible to do it like operator<(const foo ...
Hi, straight and clear as the title says :) Background: I run into some tutorial and I realized that I missed some things... So, I would really appreciate if anyone can point out any must_know_facts with an example. Thanks! ...
void fileNameProcess(char * inputName){ int size =strlen(inputName); bool change=false; char * name=inputName; for(int i =0; i<size; i++){ char temp=* (name+i); if(temp<0x10||temp>0x5b){ change=true; }else if(0x19...
When is it decided where the stack, global, and frame pointers are in memory? I'm trying to load an ELF executable into a simulator and I can't figure out what instructions load the global, stack and frame pointers into the regfile. ...
The following declaration in C: int* a, b; will declare a as type int* and b as type int. I'm well aware of this trap, but what I want to know is why it works this way. Why doesn't it also declare b as int*, as most people would intuitively expect? In other words, why does * apply to the variable name, rather than the type? Sure you ...
I require to add a string before 45byte in an existing file. I tried using fseek as bellow. int main() { FILE *fp; char str[] = "test"; fp = fopen(FILEPATH,"a"); fseek(fp,-45, SEEK_END); fprintf(fp,"%s",str); fclose(fp); return(0); } I expected that this code will add "test" in before 45 char from EOF...
Hi. My question is: when i write a function prototype in C like this: void foo(int *vector); It's the same thing to do: void foo(int vector[MAX_LENGTH]); To the function, is passed always as a pointer? The code it's the same? Thanks in advance. ...
Hey, I've got some problems with a pointer void getPartOfString(const TCHAR * wholeString) { const TCHAR * pPointer = NULL; pPointer = _tcsstr(wholeString, searchedString); //searching for a special string in string pPointer += _tcslen(searchedString); //set pointer to the beginning of the string wanted //here I want t...
please can anybody explain this code from C++ Reference site: #include <iostream> #include <memory> using namespace std; int main () { auto_ptr<int> p; p.reset (new int); *p=5; cout << *p << endl; p.reset (new int); *p=10; cout << *p << endl; return 0; } ...
I am learning C programming and I have a simple question about pointers... I used the following code to play around with pointers: #include <stdio.h> int main (int argc, const char * argv[]) { int * c; printf("%x\n",c); return 0; } When I print the value of C, I get back a 0. However, when I print &c (i.e. printf("&x\n",&c) I get ...
I've been staring at this for a while and not getting very far. FruitBasketFactory, FruitBasket, and Fruit are three classes from an API I'm using. My goal is to make a fruit basket and then retrieve the fruit. According to the FruitBasketFactory.hpp: const FruitBasket* getFruitBasket() const; and then in the FruitBasket.hpp siz...
Hi, I have a dll which requires me to set a callback function for it (actually it's a camera sdk and it will callback my function when it receives a picture). I wanna have multiple (user input) cameras but I can't. Since I should make unknown number of callback functions. the easy way is to make a class (camera) which have a function f...
Hello, I have some singleton class (please, don't speak about singleton usage). class InputSystem : boost::serialization::singleton<InputSystem> { private: boost::shared_ptr<sf::Window> mInputWindow; public: InputSystem() { mInputWindow = boost::shared_ptr<sf::Window>( new sf::Window(someARgs) ); someMethod(); } ...