Just to make things clear, I am not on the SQLite dev team, so I have no
influence on the documentation. I am just extrapolating from experience.
What should substr('abcd',0,-2) return? 'cd' or just 'd'? Or maybe just an
empty string?
If you start numbering at the left with 1, 0 is just left of the string. If you
start numbering at the right with -1, 0 is just right of the string.
Or do you take on the stance of historians: There is no year 0, there is just
1BC immediately followed by 1AD?
-----Ursprüngliche Nachricht-----
Von: sqlite-users [mailto:[email protected]] Im
Auftrag von curmudgeon
Gesendet: Montag, 26. Februar 2018 19:35
An: [email protected]
Betreff: [EXTERNAL] Re: [sqlite] Strange concatenation result
There's nothing special about Y=0. The Y can be anywhere outwith the string.
e.g.
substr('abc', 6, -4) = 'bc'
substr('abc', -5, 3) = 'a'
All substr functions should work this way. I wrote a c++ function to emulate it.
String substr(const String &Str, int Start, int Len) {
if (Str=="" || !Len) return "";
String S;
int StrLen = Str.Length();
if (Start < 0) Start = StrLen + Start + 1;
if (Len < 0) {Start += Len; Len = -Len;}
for (int i = std::max(1, Start); i <= StrLen && i < Start+Len; i++) S
+= Str[i];
return S;
}
// String is a windows wide string type
// I wrote it a while ago so it could probably be done gooder :-)
--
Sent from: http://sqlite.1065341.n5.nabble.com/
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