c++

Read hexa data from file

I'm trying to read hexa data(color value ex. 0xffffffff) from txt file... but i don't know how to read it.... i declared the color value like 'uint color' and i want to change the value though txt file. if i use int data i can use 'atoi' function, but what can i use function for uint? ...

Unicode escaping in C/C++

Hi guys! I'm having a dispute with a colleague of mine. She says that the following: char* a = "\x000aaxz"; will/can be seen by the compiler as "\x000aa". I do not agree with her, as I think you can have a maximum number of 4 hex characters after the \x. Can you have more than 4 hex chars? Who is right here? ...

How do I output an individual character when using char *[] = "something"

I've been playing with pointers to better understand them and I came across something I think I should be able to do, but can't sort out how. The code below works fine - I can output "a", "dog", "socks", and "pants" - but what if I wanted to just output the 'o' from "socks"? How would I do that? char *mars[4] = { "a", "dog", "sock", "...

Operator issues with cout

I have a simple package class which is overloaded so I can output package data simply with cout << packagename. I also have two data types, name which is a string and shipping cost with a double. protected: string name; string address; double weight; double shippingcost; ostream &operator<<( ostream &output, const Pa...

Compiler optimization causing the performance to slow down

I have one strange problem. I have following piece of code: template<clss index, class policy> inline int CBase<index,policy>::func(const A& test_in, int* srcPtr ,int* dstPtr) { int width = test_in.width(); int height = test_in.height(); double d = 0.0; //here is the problem for(int y = 0; y < height; y++) { ...

Templates, Function Pointers and C++0x

One of my personal experiments to understand some of the C++0x features: I'm trying to pass a function pointer to a template function to execute. Eventually the execution is supposed to happen in a different thread. But with all the different types of functions, I can't get the templates to work. #include <functional> int foo(void) {re...

C++ cin whitespace question

Programming novice here. I'm trying to allow a user to enter their name, firstName middleName lastName on one line in the console (ex. "John Jane Doe"). I want to make the middleName optional. So if the user enters "John Doe" it only saves the first and last name strings. If the user enters "John Jane Doe" it will save all three. I was ...

How do explicit template instantiations affect what the linker can find?

See the following code and please clear my doubts. As ABC is a template, why does it not show an error when we put the definition of the ABC class member function in test.cpp? If I put test.cpp code in test.h and remve 2, then it works fine. Why? . // test.h template <typename T> class ABC { public: void foo( T& ); void b...

How to implement an interface class using the non-virtual interface idiom in C++?

Hi all, In C++ an interface can be implemented by a class with all its methods pure virtual. Such a class could be part of a library to describe what methods an object should implement to be able to work with other classes in the library: class Lib::IFoo { public: virtual void method() = 0; }; : class Lib::Bar { p...

c++ read image pixels

I want a c++ Code to read every pixel from an image file. and i want to save the pixels like: r[] g[] b[] does somebody know how to do this? ...

How to compute a unicode string which bidirectional representation is specified?

Hello, fellows. I have a rather pervert question. Please forgive me :) There's an official algorithm that describes how bidirectional unicode text should be presented. http://www.unicode.org/reports/tr9/tr9-15.html I receive a string (from some 3rd-party source), which contains latin/hebrew characters, as well as digits, white-spaces, ...

Pointer to auto_ptr instead of a classical double pointer

Hello. I'm quite new to smart pointers and was trying to refactor some existing code to use auto_ptr. The question I have is about double pointers and their auto_ptr equivalent, if that makes sense. I have a function that accepts a double pointer as its parameter and the function allocates resources for it: void foo ( Image** img ) { ....

sizeof derived already from base

Hi, is it possible to return the sizeof a derived class already from base class/struct? imho the size of a class is a kind of property of itself, like the weight of a human being. But I don't want to write the same function in every class. many thanks in advance Oops PS: so code to make my question more clear: template <typename T> ...

Memory leak using shared_ptr

Both code examples compile and run without problems. Using the second variant results in a memory leak. Any ideas why? Thanks in advance for any help. Variant 1: typedef boost::shared_ptr<ParameterTabelle> SpParameterTabelle; struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) ...

check whether fgets would block

Hi, I was just wondering whether in C is it possible to peek in the input buffer or perform similar trickery to know whether a call to fgets would block at a later time. Java allows to do something like that by calling BufferedReader.ready(), this way I can implement console input something like this: while (on && in.ready()) { line ...

lexical_cast int to string

Is it safe to ignore exception of boost::lexical_cast when converting int to std::string? ...

How to determine the end of an integer array when manipulating with integer pointer?

Here is the code: int myInt[] ={ 1, 2, 3, 4, 5 }; int *myIntPtr = &myInt[0]; while( *myIntPtr != NULL ) { cout<<*myIntPtr<<endl; myIntPtr++; } Output: 12345....<junks>.......... For Character array: (Since we have a NULL character at the end, no problem while iterating) char myChar[] ={ 'A', 'B', 'C', 'D', 'E', '\0' }; char ...

sgetn declared deprecated

I need to change the sgetn to _Sgetn_s in boost header file here http://www.boost.org/doc/libs/1_40_0/boost/archive/basic_binary_iprimitive.hpp I don't know what the function does so i'm afraid to edit it myself. ...

Can you explain the Output ?

What should be the output of the following code and why? I am little bit confused. int a =10; printf("%d %d %d",a,a=a+10,a); ...

Simple alternative to GNU Readline library not GPL

I love the GNU readline library, but since it is under a GPL license, I can not use it for commercial software. Do you know alternatives ? I only need the commandline history and auto completion (of customer keywords and files) features. I found this link : http://github.com/antirez/linenoise which seem to be a good starting point, but...