Hi, I had just a look at the stdio.h where I could find the FILE structure definition: typedef struct { int level; /* fill/empty level of buffer */ unsigned flags; /* File status flags */ char fd; /* File descriptor */ unsigned char hold; /* Unget...
I need a language lawyer with authoritative sources. Take a look at the following test program which compiles cleanly under gcc: #include <stdio.h> void foo(int *a) { a[98] = 0xFEADFACE; } void bar(int b[]) { *(b+498) = 0xFEADFACE; } int main(int argc, char **argv) { int a[100], b[500], *a_p; *(a+99) = 0xDEADBEEF; *(b+499...
If the constructor for Door looks like this: Door::Door(Doorknob doorknob) : m_doorknob(doorknob) { } Then you would instantiate a Door like this: Doorknob doorknob; Door door(doorknob); // Does an object copy of doorknob occur here? It seems like if you store Doorknob as a pointer, you can explicitly avoid the copy: Door::Door(D...
Hi there, in the past we encountered various memory-leaks in our software. We found out that these happened mostly due to incorrect usage of our own "free"-Methods, which free Queue-Message-Data and the likes. The problem is, in our deepest tool-functions there are two methods to free up dynamically allocated memory, with the followin...
Can somebody explain why the following code is not valid? Is it because the offset for the variable named d is different than the variable named b? class Base { public: int foo; }; class Derived : public Base { public: int bar; }; int DoSomething( Base*& b ) { return b->foo; } Base* b = new Derived; Derived* d = new Derived; int mai...
Hi everyone! I have the function prototype here: extern "C" void __stdcall__declspec(dllexport) ReturnPulse(double*,double*,double*,double*,double*); I need to write some python to access this function that is in a DLL. I have loaded the DLL, but each of the double* is actually pointing to a variable number of doubles (an array), and ...
Is it possible to pass a pointer to an object into a DLL, initialize it, and then use the initialized pointer in the main application? If so how? Are there any good articles on the subject, perhaps a tutorial? I have read this article http://msdn.microsoft.com/en-us/library/ms235460.aspx But that did not seem to get me any where. Maybe ...
Ah-hoi, hoi, I'm wondering if it's ok to do something like the following: class SomeClass { int bar; }; SomeClass* foo = new SomeClass(); int offset = &(foo->bar) - foo; SomeClass* another = new SomeClass(); *(another+offset) = 3; // try to set bar to 3 Just Curious, Dan O ...
Consider this example: #include <iostream> class myclass { public: void print() { std::cout << "myclass"; } }; int main() { myclass* p = 0x0; // any address p->print(); // prints "myclass" } I didn't call the member function print through an object of type myclass. Instead I called it from a pointer to a random place in...
Hi, I am working on some software that should be used for a special type of experiment. The experiments are performed using: 1) A "Chip" (basically an XY grid of known dimensions). 2) Each Chip contains "Electrodes", identified by their X and Y coordinate on the chip and by a unique ID. Each electrode can also hold or not hold a sampl...
Hi everyone - I was reading the ctypes tutorial, and I came across this: s = "Hello, World" c_s = c_char_p(s) print c_s c_s.value = "Hi, there" But I had been using pointers like this: s = "Hello, World!" c_s = c_char_p() c_s = s print c_s c_s.value Traceback (most recent call last): File "<pyshell#17>", line 1, in <module> c...
I have some code in a couple of different functions that looks something like this: void someFunction (int *data) { data = (int *) malloc (sizeof (data)); } void useData (int *data) { printf ("%p", data); } int main () { int *data = NULL; someFunction (data); useData (data); return 0; } someFunction () and useData () ...
Ok guys, just a quick question hopefully someone can find my mistake quickly, but I just can't see it at the moment Here is my struct: typedef struct { Car *buffer[CAR_PARK_SIZE]; char *arrival_time[CAR_PARK_SIZE]; int keep_running; int size; } CarPark; typedef struct { Car *buffer...
I'm sort of learning C, I'm not a beginner to programming though, I "know" Java and python, and by the way I'm on a mac (leopard). Firstly, 1: could someone explain when to use a pointer and when not to? 2: char *fun = malloc(sizeof(char) * 4); or char fun[4]; or char *fun = "fun"; And then all but the last would set indexes 0...
I am writing a B+ tree for a variety of reasons and I am come here to ask a question about implementation of its nodes. My nodes currently look like: struct BPlusNode { public: //holds the list of keys keyType **keys; //stores the number of slots used size_t size; //holds the array of pointers to lower nodes NULL if ...
I'm working on a memory pool implementation and I'm a little confused about pointers alignment... Suppose that I have a memory pool that hands out fixed size memory blocks, at the point of memory pool creation I malloc((size)*(num of blocks)). If whats being allocated are objects and the size comes from the sizeof operator alignment sh...
The title pretty much says it all, do you prefer to see something like t_byte* (where t_byte would be a typedef for unsigned char) or unsigned char* in code? I'm leaning towards t_byte in my own libraries, but have never worked on a large project where this approach was taken, and am wondering about pitfalls. Regards, Dan O. ...
I’ve heard some words of warning against shipping an object to another memory location via memcpy, but I don’t know the specific reasons. Unless its contained members do tricky things that depend on memory location, this should be perfectly safe … or not? EDIT: The contemplated use case is a data structure like a vector, which stores o...
Hi all, I have a class A: class A { public: virtual double getValue() = 0; } And a class B: class B : public A { public: virtual double getValue() { return 0.0; } } And then in main() I do: A * var; var = new B[100]; std::cout << var[0].getValue(); //This works fine std::cout << var[1].getValue(); //This, ...
When -fomit-frame-pointer is used (automatic for various -O settings), performing a backtrace is problematic. I am wondering if there is a way of determining at compile time that the code is compiled with this switch? In that case, I could put in an #ifndef to guard against backtracing when ill-advised. Is any macro set when this -fom...