Comment by WalterBright

> What is your basis for this claim?

Great question! Here's one answer:

Having written a great deal of C code, I made a discovery about it. The first algorithm and data structure selected for a C program, stayed there. It survives all the optimizations, refactorings and improvements. But everyone knows that finding a better algorithm and data structure is where the big wins are.

Why doesn't that happen with C code?

C code is not plastic. It is brittle. It does not bend, it breaks.

This is because C is a low level language that lacks higher level constructs and metaprogramming. (Yes, you can metaprogram with the C preprocessor, a technique right out of hell.) The implementation details of the algorithm and data structure are distributed throughout the code, and restructuring that is just too hard. So it doesn't happen.

A simple example:

Change a value to a pointer to a value. Now you have to go through your entire program changing dots to arrows, and sprinkle stars everywhere. Ick.

Or let's change a linked list to an array. Aarrgghh again.

Higher level features, like what C++ and D have, make this sort of thing vastly simpler. (D does it better than C++, as a dot serves both value and pointer uses.) And so algorithms and data structures can be quickly modified and tried out, resulting in faster code. A traversal of an array can be changed to a traversal of a linked list, a hash table, a binary tree, all without changing the traversal code at all.