Re: Best way to check for an element in an array?

[Taylor Hillegeist via Digitalmars-d-learn]

On Tuesday, 22 April 2014 at 03:57:33 UTC, Timothee Cour via 
Digitalmars-d-learn wrote:
you can use stuff.canFind(2)

but sometimes it'd be more convenient to have the other way 
around (UFCS
chains etc);
how about:

bool isIn(T,T2...)(T needle, T2 haystack)
if(__traits(compiles,T.init==T2[0].init)){
  foreach(e;haystack){
    if(needle==e) return true;
  }
  return false;
}
unittest{
assert(1.isIn(3,1,2) && !4.isIn(3,1,2));
}

I like it! I didn't know you could use templates like that! 
Question though? why doesn't canFind() work on statically 
allocated arrays?

import std.stdio;
import std.algorithm;

bool contains(T)( T[] haystack,T needle){
                 foreach(T e;haystack){
                   if(needle==e) return true;
                 }
         return false;
}
unittest{
        assert([3,1,2].contains(1) && ![3,1,2].contains(4));
}

void main(string[] args)
{
    int[3] stuff=[0,1,2];
        if (stuff.contains(2))
    {
        writeln("Hello World!");
    }
        
        if (stuff.canFind(2)){ // No compile with stuff -> static
            writeln("This Also WOrks");
        }
}


On Mon, Apr 21, 2014 at 8:25 PM, Taylor Hillegeist via 
Digitalmars-d-learn <
digitalmars-d-learn@puremagic.com> wrote:

So I find myself Doing this kind of thing very frequently. I 
have a Array
of Somethings and i want to see if "something specific" is 
inside the
array. I wrote a template for it. but is this the best way to 
do this kind
of thing. I feel like it doesn't help with readability. Is 
there a better
way? Maybe i missed something in the std library.

import std.stdio;

template FNDR(T){
    bool isIn(T Element, T[] Array){
        bool rtn=false;
        foreach(T ArrayElement; Array){
            if(Element==ArrayElement){
                rtn=true;
            }
        }
    return rtn;
    }
}

void main(string[] args)
{
    int[3] stuff=[0,1,2];
    if (FNDR!int.isIn(2,stuff))
    {
        writeln("Hello World!");
    }
}


Is there a way maybe to make it look like this?

import std.stdio;

template FNDR(T){
    bool contains(T[] Array,T Element){
        bool rtn=false;
        foreach(T ArrayElement; Array){
            if(Element==ArrayElement){
                rtn=true;
            }
        }
    return rtn;
    }
}

void main(string[] args)
{
    int[3] stuff=[0,1,2];
    if (stuff.contains(2)) // Much clean! 
stuff.FNDR!int.contains(2)
doesn't work
    {
        writeln("Hello World!");
    }
}

I'm interested in what you guys think? what is the cleanest 
way to do this?