c++

Why doesn't this for-loop execute?

I'm writing a program for an exercise that will read data from a file and format it to be readable. So far, I have a bit of code that will separate a header from the data that goes under it. Here it is: int main() { ifstream in("records.txt"); ofstream out("formatted_records.txt"); vector<string> temp; vector<string> hea...

Getting the vector points of a letter in a truetype font

Since True Type fonts are just vectors, I was wondering if there was a way to get the vectors (array of points) for a letter given that i'm using the WinAPI. Thanks ...

F# performance in scientific computing

hello. I am curious as to how F# performance compares to C++ performance? I asked a similar question with regards to Java, and the impression I got was that Java is not suitable for heavy numbercrunching. I have read that F# is supposed to be more scalable and more performant, but how is this real-world performance compares to C++? s...

Why can't I assign a scalar value to a class using shorthand, but instead declare it first, then set its value?

I am writing a UTF-8 library for C++ as an exercise as this is my first real-world C++ code. So far, I've implemented concatenation, character indexing, parsing and encoding UTF-8 in a class called "ustring". It looks like it's working, but two seemingly equivalent ways of declaring a new ustring behave differently. The first way: ustri...

C++ LPTSTR to int (but memory overwrite problem using atoi)

I have the following code, m_edit is a MFC CEdit (I know I would never use MFC but project demanded it). It's a simple loop, that gets the text from a text edit, converts it to integer after getting the first line, then stores it in m_y vector. LPTSTR szTemp; vector<int> m_y; for(int i = 0; i < m_edit->GetLineCount(); i++){ szTemp ...

Fast rectangle to rectangle intersection

What's a fast way to test if 2 rectangles are intersecting? A search on the internet came up with this one-liner (WOOT!), but I don't understand how to write it in Javascript, it seems to be written in an ancient form of C++. struct { LONG left; LONG top; LONG right; LONG bottom; } RECT; bool IntersectRe...

Help with these warnings. [inheritance].

Hello there. I have a set of code, which mimics a basic library cataloging system. There is a base class named items, in which the the general id,title and year variables are defined and 3 other derived classes (DVD,Book and CD). Base [Items] Derived [DVD,Book,CD]. The programs runs, however I get the following warnings, I'm not sure ...

floating exception using icc compiler

I'm compiling my code via the following command: icc -ltbb test.cxx -o test Then when I run the program: time ./mp6 100 > output.modified Floating exception 4.871u 0.405s 0:05.28 99.8% 0+0k 0+0io 0pf+0w I get a "Floating exception". This following is code in C++ that I had before the exception and after: // before if (j < E[i]...

Why can't I pass const map structure to a function in c++?

I tried to pass const with vector it works: Ex: void damn(const vector <bool> &bb) { for (int i=0; i<bb.size(); i++) cout<<bb[i]<<endl; } But when trying with map, it does not: void pas(const map <string, float> &mm) { cout<<mm["a"]; cout<<mm["b"]; } I wonder why it doesn't. ...

Question regarding C++ Templates

I used a simple class for a test program about templates, this is what I did: template <typename T> class test { public: test<T>::test(); T out(); }; template <typename T> test<T>::test() { } T test<T>::out() { } int main() { //test<int> t; } But when I try to compile it says 'T' : undeclared identifier and use of class...

How to remove an item from a structure array in C++?

I have the following array structure (linked list): struct str_pair { char ip [50] ; char uri [50] ; str_pair *next ; } ; str_pair *item; I know to create a new item, I need to use item = new str_pair; However, I need to be able to loop through the array and delete a particular item...

Is there a way to implement OnReady() callback in Qt4?

I want to do something which will access network when a QMainWindow is ready. I suppose I should not do it in the constructor, so I try to find a signal the widget will get and try to implement something like a OnReady() call back in other UI library. But I still can not find a way to do this. Thanks a lot in advance. ...

how to write any custom data type to file using ifstream?

as question says, i want to write custom data type data of a class maybe to a file using ifstream in c++. Need help. ...

openmp in mex : stackoverflow error

i have got the following fraction of code that getting me the stack overflow error #pragma omp parallel shared(Mo1, Mo2, sum_normalized_p_gn, Data, Mean_Out,Covar_Out,Prior_Out, det) private(i) num_threads( number_threads ) { //every thread has a new copy double* normalized_p_gn = (double*)malloc(NMIX*sizeof(dou...

Assignment operator that calls a constructor is broken

I've implemented some of the changes suggested in this question, and (thanks very much) it works quite well, however... in the process I've seemed to break the post-declaration assignment operator. With the following code: #include <cstdio> #include "ucpp" main() { ustring a = "test"; ustring b = "ing"; ustring c = "- -"; ustrin...

Invoking MSYS bash from Windows cmd

I'm using GCC on Windows7 (using the TDM's build). I installed MSYS to be able to execute make and compile using makefiles. However, it is tedious to every time start up the MSYS bash shell, navigate to the directory of the project and run make. What I want is to automate this process. I prefer to have a batch file in Windows, or someth...

c++ macros question

can somebody explain the following code please? #if 1 // loop type #define FOR_IS_FASTER 1 #define WHILE_IS_FASTER 0 // indexing type #define PREINCREMENT_IS_FASTER 1 #define POSTINCREMENT_IS_FASTER 0 #else // loop type #define FOR_IS_FASTER 1 #define WHILE_IS_FASTER 0 // indexing type #define PREINCREMENT_IS_FASTER 0 #define POSTINC...

How do I define an implicit typecast from my class to a scalar?

I have the following code, which uses a Unicode string class from a library that I'm writing: #include <cstdio> #include "ucpp" main() { ustring a = "test"; ustring b = "ing"; ustring c = "- -"; ustring d; d = "cafe\xcc\x81"; printf("%s\n", (a + b + c[1] + d).encode()); } The encode method of the ustring class instances co...

Who architected / designed C++'s IOStreams, and would it still be considered well-designed by today's standards?

First off, it may seem that I'm asking for subjective opinions, but that's not what I'm after. I'd love to hear some well-grounded arguments on this topic. In the hope of getting some insight into how a modern streams / serialization framework ought to be designed, I recently got myself a copy of the book Standard C++ IOStreams and Lo...

Any free memory leak detector for Qt?

I'm looking for free memory leak detector for Qt. I use Qt Creator 1.3 with Qt version 4.6 (32 bit). The platform is Windows 7 Ultimate. Thanks. ...