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Quick Q: With arrays, why is it the case that a[5] == 5[a]?

By Adrien Hamelin | Jun 4, 2019 11:01 AM | Tags: intermediate

Quick A: See below

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With arrays, why is it the case that a[5] == 5[a]?

The C standard defines the [] operator as follows:

a[b] == *(a + b)

Therefore a[5] will evaluate to:

*(a + 5)

and 5[a] will evaluate to:

*(5 + a)

a is a pointer to the first element of the array. a[5] is the value that's 5 elements further from a, which is the same as *(a + 5), and from elementary school math we know those are equal (addition is commutative).

The Difference Between std::copy_backward and std::copy with Reverse Iterators--Jonathan Boccara

By Adrien Hamelin | Jun 3, 2019 11:47 AM | Tags: stl intermediate

What do you think?

The Difference Between std::copy_backward and std::copy with Reverse Iterators

by Jonathan Boccara

From the article:

A couple of months ago, I made a talk at the ACCU conference about learning every algorithm there is in the STL. Amongst them, we covered std::copy_backward, that makes a copy of a source range to a destination range, starting from its end and working its way back to the beginning.

In the questions session at the end of the talk, attendant Oscar Forner rose an interesting point: is there any difference between performing a std::copy_backward versus performing a simple std::copy on the reverse iterators from the source collection?

CppCast Episode 200: Simplifying C++ with Herb Sutter

By robwirving | May 31, 2019 07:20 AM | Tags: None

Episode 200 of CppCast the first podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by ISO chair Herb Sutter to discuss C++20 and his goal of simplifying the C++ of the future.

CppCast Episode 200: Simplifying C++ with Herb Sutter

by Rob Irving and Jason Turner

About the interviewee:

Herb Sutter is an author, chair of the ISO C++ committee, and a systems languages architect at Microsoft.

strong_typedef - Create distinct types for distinct purposes--Anthony Williams

By Adrien Hamelin | May 30, 2019 01:39 PM | Tags: community

A common problem with a common solution made easier.

strong_typedef - Create distinct types for distinct purposes

by Anthony Williams

From the article:

One common problem in C++ code is the use of simple types for many things: a std::string might be a filename, a person's name, a SQL query string or a piece of JSON; an int could be a count, an index, an ID number, or even a file handle. In his 1999 book "Refactoring" (which has a second edition as of January 2019), Martin Fowler called this phenomenon "Primitive Obsession", and recommended that we use dedicated classes for each purpose rather than built-in or library types...

Heterogeneous Lookup in Ordered Containers, C++14 Feature--Bartlomiej Filipek

By Adrien Hamelin | May 29, 2019 12:26 PM | Tags: stl performance c++14

Did you know?

Heterogeneous Lookup in Ordered Containers, C++14 Feature

by Bartlomiej Filipek

From the article: 

If you have a map of strings, like std::map<std::string, int> m; and you want to find some element by m.find("abc"). Do you have to pay the price and construct a std::string object? Can you optimize it?

Let’s have a look at one feature enabled in C++14 that might help optimize such container access...