How to loop through characters of a string in D language?

rumbu rumbu at
Thu Dec 23 16:23:32 UTC 2021

On Thursday, 23 December 2021 at 07:14:35 UTC, Salih Dincer wrote:

> It seems faster than algorithms in Phobos. We would love to see 
> this in our new Phobos.

> Replace: 436 msecs
> Malloc : 259 msecs
> */

It seems because MallocReplace is cheating a lot:
- it is not called through another function like replace is 
- accesses directly the constant str;
- assumes that it has a single character to replace;
- assumes that the character will be deleted not replaced with 
- assumes that the character is always ';'
- assumes that the replacing string is not bigger than the 
replaced one, so it knows exactly how much space to allocate;
- does not have any parameter, at least on x86 this means that 
there is no arg pushes when it's called.
- does not return a string, just compares its result with another 

Since we already know all this stuff, we can go further :)

string superFast()
     enum r = str.replace(";", "");
     return r;

> Replace: 436 msecs
> Malloc : 259 msecs
> SuperFast: 0 msecs

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