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Address and Thread Sanitizers in GCC -- Red Hat Developer Blog

By Marcin Hoppe | Dec 12, 2014 07:40 AM | Tags: gcc basics

A short article about two error-detection features in GCC:

Address and Thread Sanitizers in GCC

by Dodji Seketeli on Red Hat Developer Blog

From the article:

Since their 4.8 version, the C and C++ compilers of the GNU Compiler Collection are equipped with built-in memory and data race errors detectors named Address Sanitizer and Thread Sanitizer.

This article intends to quickly walk you through the highlights of these two interesting tools.

ccache 3.2 released

By Razvan Pascalau | Dec 8, 2014 12:05 AM | Tags: tools product compiler basics

Version 3.2 of ccache was recently released. It can help you be more productive as "It speeds up recompilation by caching previous compilations and detecting when the same compilation is being done again" (from the official page). The new version that has been released is a feature version which means lots of goodies and new features.

ccache 3.2 released

From the announcement:

  • Added support for configuring ccache via one or several configuration files instead of via environment variables. Environment variables still have priority but are no longer the recommended way of customizing ccache behavior. See the manual for more information.
  • Added support for compiler error/warning messages with color.
  • Made creation of temporary directories and cache directories smarter to avoid unnecessary stat calls.
  • Improved efficiency of the algorithm that scans for __DATE__ and __TIME__ tokens in the hashed source code.
  • Added support for several binaries (separated by space) in CCACHE_PREFIX.
  • The -c option is no longer passed to the preprocessor. This fixes problems with clang and Solaris’s C++ compiler.
  • ccache no longer passes preprocessor options like -D and -I to the compiler when compiling preprocessed output. This fixes warnings emitted by clang.

And much more ...

 

Overload 124 is now available

By Blog Staff | Dec 4, 2014 09:13 PM | Tags: intermediate basics

overload-124.PNGOverload 124 is now available. It contains the following C++-related articles, and more:

 

Overload 124

Designing Observers in C++11

The observer pattern is over two decades old. Alan Griffiths fits a venerable design pattern into a contemporary context.

Order Notation in Practice

What does complexity measurement mean? Roger Orr reminds us of the academic definition and looks at some real life situations... std::sort is faster than qsort which can come as a surprise to those who assume C is always faster than C++.

Common reasons of using namespaces in C++ projects -- CoderGears Team

By Marcin Hoppe | Dec 4, 2014 03:20 AM | Tags: basics

CoderGears team draws some conclusions on how namespaces are used in C++ projects:

Common reasons of using namespaces in C++ projects

by CodeGears Team

From the article:

Namespaces in C++ are most often used to avoid naming collisions. Although namespaces are used extensively in recent C++ code, most older code does not use this facility. After exploring the source code of many C++ projects, here are some common reasons of using the namespaces in these projects...

A gotcha with Boost.Optional --Andrzej KrzemieĊ„ski

By Razvan Pascalau | Dec 3, 2014 11:50 AM | Tags: boost basics

Have you used the Boost.Optional library? There is one thing you might need to keep an eye on as explained by Andrzej.

  A gotcha with Optional

  by Andrzej Krzemieński

From the article:

This post is about one gotcha in Boost.Optional library. When starting to use it, you might get the impression that when you try to put optional<T> where T is expected, you will get a compile-time error. In most of the cases it is exactly so, but sometimes you may get really surprised...

Quick Q: How do I add elements to a 2D vector of ints?--StackOverflow

By Jared Mulconry | Dec 2, 2014 03:56 AM | Tags: basics

Quick A: Index into the desired sub-vector and call push_back.

Recently on SO:

Inserting elements into 2D vector

So I'm creating a class that implements an adjacency list. Currently in my class definition I initialized two vectors:

vector<vector<int>> adjList;
vector<int> neighbors;

and I declared two functions that I plan to use to make it:

bool constructAdjList();
bool insertIntoAdjList(int, int);

It's getting difficult wrapping my head around 2D vectors. I understand that it is essentially a vector of vectors, but I'm confused about how to insert a new value into one of the "subvectors". For example, I am able to create an adjacency list in createAdjList that is empty with the following loop:

for (int i = 0; i < numOfValues; i++){
    neighbors.push_back(0);
    adjList.push_back(neighbors);
    neighbors.clear();
}

But how can I say, push_back the value 5 to the 4th vector in adjList, which would be represented in my insertIntoAdjList function as

insertIntoAdjList(4, 5);

I know I can access a specific value in a 2D vector by saying adjList[4][1], but how can I push one onto it?

Thanks!

Quick Q: Does std::vector resize automatically when inserting new elements?--StackOverflow

By Jared Mulconry | Nov 28, 2014 09:54 AM | Tags: basics

Quick A: Yes.

Recently on SO:

Do Vectors resize automatically?

I am very sorry that I am asking such a beginner question but I am finding contradictory information online. I would ask at University but it is out until February next year.

Do Vectors resize automatically? Or do you need to check the current size periodically and resize when you need more room. It looks to be resizing for me automatically but I'm not sure if that is a feature or the compiler waving a magic wand.

Quick Q: What type do lambdas get compiled into? -- StackOverflow

By Blog Staff | Nov 14, 2014 09:37 AM | Tags: basics

Quick A: A compiler-generated type that stores the captured variables in its data members, and exposes the function signature and body as its operator().

Recently on SO:

What type do lambdas get compiled into?

As I know all data types must be known at compile time, and lambda is not a type. Does lambda got translated into anonymous struct with operator() or std::function wrapped?

For example,

std::for_each(v.begin(), v.end(), [](int n&){n++;});