私の上司は、配列内のアイテムを検索し、その値が発生するインデックス/インデックスを彼に与えるメカニズムを実装するようになりました。

あなたのタスク：

配列と値（String、Integer、Float、またはBoolean）を受け取り、値が発生する配列のインデックスを返すプログラムまたは関数を作成します（インデックスが0または1のいずれか）。値が配列にない場合、空の配列を返します。

入力：

Aに存在する場合と存在しない場合がある配列Aと値V。

出力：

VがAで発生するインデックスを含む配列、またはVがAで発生しない場合は空の配列。

テストケース：

テストケースは0ベースであることに注意してください。

12, [12,14,14,2,"Hello World!",3,12,12]         -> [0,6,7]
"Hello World", ["Hi", "Hi World!", 12,2,3,True] -> []
"a", ["A",True,False,"aa","a"]                  -> [4]
12, [12,"12",12]                                -> [0,2]

得点：

これはcode-golfであるため、バイト単位の最低スコアが優先されます。

Pyth、2バイト

0インデックス。

xE

オンラインでお試しください！または、すべてのテストケースを確認します

説明

xEQ  - Full Program. Takes Input from standard input. Q means evaluated input and is implicit at the end of the program.

x   - Get all the indexes of x in y
 E  - Evaluated Input #2 - The value
  Q - The list - Evaluated Input #1

MATL、2バイト

mf

m消費二つの引数、およびチェック他の引数と等しいかどうかを、配列の各要素は、fアレイのtruthyエントリのインデックスを返します。

オンラインでお試しください！

Python 3、45バイト

@EriktheOutgolferと@Chris_Randsのおかげで-3バイト

lambda y,x:[i for i,j in enumerate(x)if j==y]

テストスイート。

今日学びましたenumerate(x) == zip(range(len(x)),x)。

Python 3、47バイト

lambda n,l:[x for x in range(len(l))if l[x]==n]

オンラインでお試しください！または、すべてのテストケースを確認します

R（+ pryr）、20バイト

pryr::f(which(a==b))

関数に評価する

function (a, b) 
which(a == b)

a検索する値とbベクトル、またはその逆のいずれかです。長さが等しくない2つのベクトル（Rで1つの値が長さ1のベクトルとしてカウントされる）が提示されると、Rは短い方をラップして長い方の長さに一致させます。次に、平等がチェックされます。これにより、論理ベクトルが生成されます。whichこのベクトルが真であるインデックスを提供します。

オンラインでお試しください！

JavaScript、39バイト

e=>a=>[...a.keys()].filter(i=>a[i]===e)

f=
e=>a=>[...a.keys()].filter(i=>a[i]===e)

console.log(f(12)([12,14,14,2,"Hello World!",3,12,12]));
console.log(f("Hello World")(["Hi", "Hi World!", 12,2,3,true]));
console.log(f("a")(["A",true,false,"aa","a"])); 
console.log(f(12)([12,14,14,2,"Hello World!",3,12,'12']));

上記のスニペットはすべてのブラウザで機能するとは限りません。そのため、ここにTIOリンクがあります。

JavaScript（ES6）、44 43バイト

^{取り消し線44は、まだ規則的な44です;（}

v=>a=>a.map((x,i)=>x===v&&++i).filter(x=>x)

@Arnauldのおかげで1バイト節約

let f=
v=>a=>a.map((x,i)=>x===v&&++i).filter(x=>x)
;

console.log(f(12)([12,14,14,2,"Hello World!",3,12,12]));         // => [1,7,8]
console.log(f("Hello World")(["Hi", "Hi World!", 12,2,3,true])); // => []
console.log(f("a")(["A",true,false,"aa","a"]));                  // => [5]

05AB1E、4バイト

QāsÏ

オンラインでお試しください！

1インデックス付き。

C＃、88 72バイト

using System.Linq;a=>o=>a.Select((i,n)=>o.Equals(i)?n:-1).Where(n=>n>=0)

@LiefdeWenのおかげで16バイト節約されました。

オンラインでお試しください！

ゼリー、3バイト

⁼€T

オンラインでお試しください！

-1 氏Xcoderに感謝します。（二項鎖）

Haskell、41 39バイト

v!l=fst<$>(filter((==v).snd)$zip[1..]l)

オンラインでお試しください！

@flawrのおかげで2バイト節約

Haskellは静的に型付けされているため、テストケースを実行するために少しの回避策を使用する必要がありました。

殻、5バイト

`fNm=

オンラインでお試しください！1インデックス付き。

説明

       -- implicitly input a value v and a list L
   m=  -- map "equals v" over the list L, resulting in a list of truthy and falsy values
`fN    -- filter the natural numbers N by discarding the numbers at falsy positions 
          and keeping the ones at truthy positions

ルビー、46 40 39バイト

->e,a{i=-1;a.map{|x|i+=1;x==e&&i}-[!1]}

7バイト保存しました!!! Eric Duminilに感謝します。

オンラインでお試しください。

ルビー、38バイト

->e,a{a.each_index.select{|x|a[x]==e}}

オンラインでお試しください！

Google Sheets, 101 bytes

=IfError(Join(",",Filter(Column(Offset(A1,0,0,1,Counta(Split(B1,",")))),Exact(Split(B1,","),A1))),"")

Value V in A1 and array A in B1 with each entry separated by a comma. Null entires are not allowed (row 5 below shows what happens).

Explanation:

Offset(A1,0,0,1,Counta(Split(B1,","))) returns a range that is one row tall and as many columns wide as there are entries in A1.

=IfError(Join(",",Filter(Column(~),Exact(Split(B1,","),A1))),"") filters the column numbers of that range based on whether or not the value in A1 is exactly each of the values in B1 and concatenates them all in a comma-delineated list.

Clojure, 40 bytes

First attempt at code golf.

keep-indexed maps a function over a collection here, passing the current index into the callback and yielding any non-nil return values.

(fn[a b](keep-indexed #(if(= %2 a)%1)b))

Try it online!

APL (Dyalog Unicode), 2 bytes^SBCS

Takes item to look for as left argument (must be scalar to find an item of the lookup array rather than a subarray) and the lookup array (which may have up to 15 dimensions) as right argument. Returns list of indices, each of which may has as many elements as the number of dimensions in the lookup array.

⍸⍷

Try it online!

⍸ ɩndices where

⍷ found

Batch, 86 bytes

@set i=0
:g
@if "%~2"=="" exit/b
@if %1==%2 echo %i%
@set/ai+=1
@shift/2
@goto g

Takes input as command line parameters (value then the array elements as separate parameters). Note: String quoting is considered part of the match e.g. "1" won't equal 1 (would cost 6 bytes).

Python 2, 49 bytes

lambda l,v:filter(lambda i:l[i]==v,range(len(l)))

Try it online!

Not short enough, but I thought it was cool. ¯\_(ツ)_/¯

Perl 5, 28 bytes

sub{grep$_[$_]eq$_[0],1..@_}

Try it online!

The output is 1-indexed.
An anonymous function is quite unusual for Perl, but it happens to be the shortest I could think of. grep ..., 1 .. @_ iterates over the indexes of the input array (actually it goes one cell beyond the last, but it doesn't matter), keeping only the index that satisfy $_[$_]eq$_[0], ie. the ones where the value of the element ($_[$_]) is the same as the value we need to keep ($_[0]).

Slightly longer (31 bytes (30 + -l flag)), but as a full program:

$@=<>;$@eq$_&&print$.-1while<>

Try it online!

Haskell, 37 33 bytes

import Data.List
findIndices.(==)

Thanks @Laikoni for -4 bytes!

Try it online!

Java 8, 146 113 112 111 110 108 bytes

import java.util.*;l->o->{List r=new Stack();for(int i;(i=l.indexOf(o))>-1;l.set(i,null))r.add(i);return r;}

-2 bytes thanks to @TAsk by using Vector instead of ArrayList.
-1 byte by using Stack instead of Vector.
-2 bytes thanks to @Jakob by inputting a ArrayList instead of an array.

0-indexed

Explanation:

Try it here.

import java.util.*;    // Required import for Vector and Vector
l->o->{                // Method with List and Object parameters
  List r=new Stack();  //  Result-list
  for(int i;(i=l.indexOf(o))>=-1;
                       //  Loop as long as we can find the object in the list
    l.set(i,null))     //   After every iteration, remove the found item from the list
      r.add(i);        //    Add the index to the result-list
                       //  End of loop (implicit / single-line body)
  return r;            //  Return the result-List
}                      // End of method

05AB1E, 4 bytes

Qƶ0K

Try it online!

It is 1-indexed, as shown below:

IN A-#------------------------> [2,3,3,3,4]
IN B-#------------------------> 3
-----#------------------------+-----------------
Q    # Vectorized equivalence | [0,1,1,1,0]
 ƶ   # Lift by index          | [0,2,3,4,0]
  0K # Remove zeros           | [2,3,4]

Mathematica, 12 bytes

Position@##&

1-Indexed

input [Array,Value]

[{12, 14, 14, 2, "Hello World!", 3, 12, 12}, 12]

output

{{1}, {7}, {8}}

Haskell, 29 bytes

e#l=[i|(i,h)<-zip[0..]l,h==e]    

Try it online!

Japt, 9 bytes

mȶV©YÄÃf

1-indexed.

Japt input doesn't support booleans, so they have been replaced with 0 and 1 in the test cases.

Try it online! with the -Q flag to format the array output.

0-indexed Solution, 11 bytes

l o f@gX ¶V

Try it online!

Perl 6, 21 bytes

{grep :k,*===$^v,@^z}

Try it online!

The :k adverb to grep tells it to return the matching keys (indices) of the input sequence that match the predicate * === $^v.

If strings and numbers were considered equivalent, one could use a grep predicate of just $^v instead of * === $^v.

Common Lisp, 66 bytes

(lambda(x s)(loop as i in s as j from 0 when(equal i x)collect j))

Try it online!

TXR Lisp, 26 bytes

(op where(op equal @@1)@2)

In other words, "Where is argument 2 equal to argument 1?"

Run:

1> (op where(op equal @@1) @2)
#<interpreted fun: lambda (#:arg-01-0166 #:arg-02-0167 . #:rest-0165)>
2> [*1 12 #(12 14 14 2 "Hello world!" 3 12 12)]
(0 6 7)
3> [*1 "Hello World" #("Hi" "Hi world!" 12 2 3 t)]
nil

Clojure, 39 38 bytes

#(filter(comp #{%2}%)(range(count %)))

A bit obscure :) The first input argument is a vec of values and the second one is the searched value. % maps indexes to values, and the set #{%2} returns truthy (the input argument %2) or falsy nil for that value. comp composes these together.

C 340 362 166 115 Bytes

Hello all. My first time here. I figured since I enjoy (attempting) to write optimized code I may as well give this a try.

@Rodney - ~39 bytes from the includes

@Zacharý - 7 bytes with implicit typing

0-indexed.

How to Run:

As per @Arnolds suggestion, the program takes arguments in a much more C friendly manner. This let me reduce the size of the file by a little more than half.

The arguments should be passed in the following order value [element1 ...] where braces indicate optional arguments

You may or may not have to add escaped quotes to any strings that are provided in order to satisfy the condition of 12 != "12". On my system the this can be done in the following manner

prog-name.exe 12 3 "Hello" 12 4 "12"
Returns [2,4]     < This is incorrect

prog-name.exe 12 3 "\"Hello\"" 12 4 "\"12\""
Returns [2]       < Correct

golfed

#define P printf(
b=0;main(int c,char**v){P"[");for(--c;c-1;c--)b|=strcmp(v[1],v[c])?0:P b?",%i":"%i",c-2);P"]");}

ungolfed

#define P printf(

//Implicit only works in global(I totally knew this after almost 4 years of C :P)
b = 0;
main(int c,char**v)
{

    P"[");

    //match loop
    //b is used to determine if this is the first iteration. it can be assumed that printf will always return >0
    //subract two from c to get correct index number of match
    for(--c; c-1; c--)
        b |= strcmp(v[1], v[c]) ? 0 : P b ? ",%i" : "%i", c-2);

    P"]");

    return 0;
}