cplusplus.co.il

Archive for December 2009

Are you familiar with the new, all-mighty, arrow “–>” operator in C++ ?

#include <iostream>

int main () {
    unsigned count = 30;
    while (count --> 0) // count goes to zero
        std::cout << count << std::endl;
}

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The future standard extension (some of it is described in the Technical Report on C++ Standard Library Extensions – TR1) is going to include many libraries already contained within boost. One such library is boost’s Smart Pointers.

In this post I would like to show an interesting use-case of the smart_ptr class, through what I consider to be a less commonly known constructor.

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Project Euler

Posted on: 14/12/2009

I know I’m a little late, but I’ve only recently discovered the interesting site of projecteuler.net. For anybody not familiar with it, Project Euler is a site offering a vast collection of programming puzzles of mathematical nature for anybody to solve. It has a ranking system for its members, allowing every member to see others’ statistics with solving the offered puzzles. Most of the puzzles are pretty hard, even for the gifted mathematicians among us, and the majority of them can not be solved using brute force methods (it would just take far too long), so usually an efficient algorithm is required. Once you solve a problem you gain access to a forum thread about the problem, its solution, and the various techniques and algorithms other users came up with.

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boost::optional is a very handy generalization of returning a null when there’s nothing to return. Consider a function such as strstr – either the required sub-string is found within the given string, in which case a pointer to it is returned, or a NULL value is returned to indicate that there was no such sub-string. In terms of boost::optional we would either return the same pointer to the occurrence of that sub-string (as before), or we would simply return nothing – no value at all. In this post we will demonstrate the usage of boost::optional and discuss its implementation.

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If you ever try to define a public custom operator new while keeping the corresponding delete operator private, you’ll end up unable to compile any code that actually invokes the public operator new. The reasoning is quite interesting.

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