On Tuesday, 14 February 2012 at 21:09:09 UTC, Ali Çehreli wrote:
On 02/14/2012 12:59 PM, RenatoL wrote:
mmmhhh.... this is interesting nevertheless i don't understand
the
solution of my problem, and i cannot even understand it's
origin:
void main()
{
string s1 = "abcd";
s1 = s1[stride(s1,0)..1] ~ 'r' ~ s1[2..$];
writeln(s1);
}
why there is not way i cannot achive "arcd"?
import std.stdio;
import std.utf;
void main()
{
string s1 = "abcd";
immutable firstCharStride = stride(s1, 0);
immutable secondCharStride = stride(s1, firstCharStride);
auto firstPart = s1[0..firstCharStride];
auto lastPart = s1[firstCharStride + secondCharStride..$];
s1 = firstPart ~ 'r' ~ lastPart;
writeln(s1);
}
Ali
I have come across similar problems using stride.
Andrei Alexandrescu writes in his book on D that it is a subtle
bug, if strings are not sliced using stride(s, index). However,
if index is the length of another string there might be a
mismatch, because stride() returns the "number of bytes in the
UTF-8/16/32 sequence" which may not correspond to length/the
index needed.
E.g. if you have a string "chat" and you want to slice it as
follows:
auto word = "chat";
// Do some regex search ...
// m[0] is the matched start sequence "ch"
auto substring = word[m[0].length..$]; // "at"
Using stride() returns 1 and not 2 (length of "ch"), so you'd get
"hat" instead of "at".
To avoid this and keep it "legal", is it possible to determine a
string's length with std.utf.count() to determine the length of a
string via utf code points (or toUCSindex())?
auto substring = word[std.utf.count(m[0])..$]; // "at"
