how to erase the file contents of text file in python and c++?
i have text file which i want to erase in C++ and python . How to do it?Do i have to assign the file pointer to a null value string? ...
c++
Driver denied access to PCI card
We wrote a Windows device driver to access our custom PCI card. The driver uses CreateFile to get a handle to the card. We recently had trouble at one installation were the card appeared to stop working. We tried replacing the card (the replacement appeared not work either). The computer vendor replaced the motherboard and both cards...
Determining if an unordered vector<T> has all unique elements
Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) {...
vss intializefor backup fails with return code E_UNEXPECTED
#include "vss.h" #include "vswriter.h" #include <VsBackup.h> #include <stdio.h> #define CHECK_PRINT(result) printf("%s\n",result==S_OK?"S_OK":"error") int main(int argc, char* argv[]) { BSTR xml; LPTSTR errorText; IVssBackupComponents *VssHandle; HRESULT result = CreateVssBackupComponents(&VssHandle); CHECK_PRINT(result); resul...
How do i add .pdb file associated with a lib file?
How do i add .pdb file associated with a lib file? I am importing a .lib file in a C++ project. When I build it i get an error saying that vc90.pdb does not contains the debug information. I have the pdb file associated with the library. how can i add it to my current project. Thanks ...
How to free static member variable in C++?
Can anybody explain how to free memory of a static member Variable? In my understanding it can only be freed if all the instances of the class are destroyed. I am a little bit helpless at this point... Some Code to explain it: class ball { private: static SDL_Surface *ball_image; }; //FIXME: how to free static Variable? SDL_Sur...
How to ensure that you are building against STLport.
I am using Visual C++ 2005 to build a couple of libraries and an executable. I include the STLport location in the Additional Include Path of the libraries and include the library in the input to linker for executable. The library however seems to reffer to stl symbols (such as string) without the stl port namespace. This results in a l...
When is ¦ not equal to ¦?
Background. I'm working with netlists, and in general, people specify different hierarchies by using /. However, it's not illegal to actually use a / as a part of an instance name. For example, X1/X2/X3/X4 might refer to instance X4 inside another instance named X1/X2/X3. Or it might refer an instance named X3/X4 inside an instance n...
How do I use try...catch to catch floating point errors?
I'm using c++ in visual studio express to generate random expression trees for use in a genetic algorithm type of program. Because they are random, the trees often generate: divide by zero, overflow, underflow as well as returning "inf" and other strings. I can write handlers for the strings, but the literature left me baffled about the...
C++ Code Clarification Needed..
Hi guys I'm trying to understand what the code below says: struct compare_pq; struct compare_pq { bool operator() (Events *& a, Events *& b); }; std::priority_queue<Events *, std::vector<Events *>, compare_pq> eventList; i looked at what priority_queue is and how its declared but can't quit understand what compare_pq is doing ...
Code coordinates to match compass bearings
Right now in Matlab (0,0) is the origin, 0 degrees / 2pi would be to the right of the cartesian plane and angles are measured counter clockwise with 90 degrees being at the top. I'm trying to write a simulator where the coordinates would match a compass bearing. 0/360 degrees or 2pi would be at the top and 90 degrees would be on the ri...
Objects of the same name in base and derived class not getting flagged as an error
class Base { public: type1 m_Pants; }; class Derived : Base { public: type2 m_Pants }; This essentially didn't get flagged as an error, but was creating all kinds of clobbering and issues throughout a project. Does anyone know of a technicality that wouldn't flag this? ...
Invalid function declaration. DevC++
Why do I get invalid function declaration when I compile the code in DevC++ in Windows, but when I compile it in CodeBlocks on Linux it works fine. #include <iostream> #include <vector> using namespace std; //structure to hold item information struct item{ string name; double price; }; //define sandwich, chips, and drink str...
C++ IO with Hard Drive
I was wondering if there was any kind of portable (Mac&Windows) method of reading and writing to the hard drive which goes beyond iostream.h, in particular features like getting a list of all the files in a folder, moving files around, ect. I was hoping that there would be something like SDL around, but so far I havn't been able to find...
How to declare a vector or array of reducer objects in Cilk++?
Hi All, I had a problem when I am using Cilk++, an extension to C++ for parallel computing. I found that I can't declare a vector of reducer objects: typedef cilk::reducer_opadd<int> T_reducer; vector<T_reducer> bitmiss_vec; for (int i = 0; i < 24; ++i) { T_reducer r; bitmiss_vec.push_back(r); } However, when I compile the cod...
Visual Studio 2005 C++ Application Wants To Run As Admin
I wrote a simple c++ application in Visual Studio 2005 but when I compile it, the executable wants to run as admin. I tried deleting the manifest but it still wants to run as admin. I am running Windows Vista Home premium. Any help would be appreciated! ...
Implementing Operator Overloading with Logarithms in C++
Hello my friends, I'm having some issues with implementing a logarithm class with operator overloading in C++. My first goal is how I would implement the changeBase method, I've been having a tough time wrapping my head around it. I have tried to understand the math behind changing the base of a logarithm, but i haven't been able to....
Calculating depth and descendants of tree
Can you guys help me with the algorithm to do these things? I have preorder, inorder, and postorder implemented, and I am given the hint to traverse the tree with one of these orders. I am using dotty to label (or "visit") the nodes. Depth is the number of edges from the root to the bottom leaf, so everytime I move, I add +1 to the dept...
c++ vector.push_back error: request for member 'push_back'..., which is of non-class type 'vector(char, allocator(char)) ()()'
I'm using Cygwin with GCC, and ultimately I want to read in a file of characters into a vector of characters, and using this code #include <fstream> #include <vector> #include <stdlib.h> using namespace std; int main (int argc, char *argv[] ) { vector<char> string1(); string1.push_back('a'); return 0; } generates this c...
How to find the length of a parameter pack ?
Hi All, Suppose I have a variadic template function like template<typename... Args> unsigned length(Args... args); How do I find the length of the parameter list using the length function ? ...