On Saturday, 17 August 2024 at 05:28:37 UTC, Bruce wrote:
Surely D must be an indexOf function that works on
arrays?
Something like...
string[] arr = ["pa", "db", "wb", "ha", "wa"];
int i = arr.indexOf("ha");
But, this is not satisfying. The Phobos library should
have this function.
I've noticed that you are looking for items in an array, not
substrings in a string.
For that you can use `countUntil`:
```
import std.stdio: writeln;
import std.algorithm.searching : countUntil;
void main()
{
const words = ["hello", "world", "bye"];
const idx = words.countUntil("world");
if (idx == -1)
{
writeln("Could not find target word");
}
else
{
writeln("Found word at index ", idx);
}
}
```
But notice that working in D, you probably should take advantage
of slices, as they're so powerful... `indexOf` and `countUntil`
are normally used to find a sub-sequence you're interested in,
which in other languages requires you to manually do based on the
indexes... but perhaps in D you could use the very appropriately
named `find` function to just obtain the relevant slice directly:
```
import std.stdio: writeln;
import std.algorithm.searching : find;
void main()
{
const words = ["hello", "world", "bye"];
const subSeq = words.find("world");
if (subSeq.length > 0)
{
writeln("Found it! ", subSeq);
}
else
{
writeln("Cannot find it!");
}
}
```
Notice that `find` returns a slice, but this is very cheap in D
as it's just a length and a pointer to the original slice's
array, it won't copy the array if you don't modify anything.
