On Saturday, 30 July 2022 at 21:48:35 UTC, rikki cattermole wrote:
It is a pretty straight forward.
You tried to access memory out of bounds of the slice.
https://github.com/pascal111-fra/D/blob/main/dcollect.d#L34
That for loop is problematic in a number of ways.
You should not use int, or uint to index into memory, only
size_t should be used. It is an alias to either uint or ulong
based upon the size of a pointer.
```d
for(size_t i = ch.length - 1; i >= 0; i--)
```
Would be the corrected line.
However, it is still not correct, what happens when ch.length
is zero? It'll wrap around and become a very large number. That
is most likely what happened here.
To do this safely in D, use the foreach_reverse statement
instead. There are very few reasons to use for loops in D.
https://dlang.org/spec/statement.html#foreach-range-statement
Adjusted:
```d
foreach_reverse(i; 0 .. ch.length)
```
However this is not efficient as you are reallocating
constantly.
```d
char[] ch_rev;
ch_rev.length = ch.length;
size_t offset;
foreach_reverse(c; ch)
ch_rev[offset++] = c;
```
Your suggestion works. It seems a problem with that "for" loop,
but I don't know exactly from where it got a 0 or subtracted of 0.
I changed data types of some parameters and for loops, and
changed that for loop as you suggested:
https://github.com/pascal111-fra/D/blob/main/dcollect.d
The program works fine now:
https://i.postimg.cc/3wkgXmVs/Screenshot-from-2022-07-31-00-04-23.png
