LINQ allows you to convert string[] to int[] in a single line of code.

Problem

I have a string representation of an array of integers:

var arr = new string[] { "1", "2", "3", "4" };

To push it any farther, I’ll need an array of’real’ integers:

void Foo(int[] arr) { .. }

I attempted to cast int, but it failed:

Foo(arr.Cast<int>.ToArray());

What I can do next is:

var list = new List<int>(arr.Length);
arr.ForEach(i => list.Add(Int32.Parse(i))); // maybe Convert.ToInt32() is better?
Foo(list.ToArray());

or

var list = new List<int>(arr.Length);
arr.ForEach(i =>
{
   int j;
   if (Int32.TryParse(i, out j)) // TryParse is faster, yeah
   {
      list.Add(j);
   }
 }
 Foo(list.ToArray());

However, both appear to be unattractive.

Is there another method to finish the job?

Asked by abatishchev

Solution #1

The Array can be used with an array. Method ConvertAll:

int[] myInts = Array.ConvertAll(arr, s => int.Parse(s));

Marc Gravell pointed out that the lambda can be eliminated, resulting in the following shorter version:

int[] myInts = Array.ConvertAll(arr, int.Parse);

A LINQ solution is similar, except that to acquire an array, you’ll need to add the ToArray call:

int[] myInts = arr.Select(int.Parse).ToArray();

Answered by Ahmad Mageed

Solution #2

EDIT: to convert to array

int[] asIntegers = arr.Select(s => int.Parse(s)).ToArray();

This ought to suffice:

var asIntegers = arr.Select(s => int.Parse(s));

Answered by Simon Fox

Solution #3

Here are some tips for avoiding exceptions when using.Parse. Alternatives to TryParse

Only parsable items should be used:

string[] arr = { null, " ", " 1 ", " 002 ", "3.0" };
int i = 0; 
var a = (from s in arr where int.TryParse(s, out i) select i).ToArray();  // a = { 1, 2 }

or

var a = arr.SelectMany(s => int.TryParse(s, out i) ? new[] { i } : new int[0]).ToArray();

Alternatives to utilizing 0 for non-parsable components include:

int i; 
var a = Array.ConvertAll(arr, s => int.TryParse(s, out i) ? i : 0); //a = { 0, 0, 1, 2, 0 }

or

var a = arr.Select((s, i) => int.TryParse(s, out i) ? i : 0).ToArray();

C# 7.0:

var a = Array.ConvertAll(arr, s => int.TryParse(s, out var i) ? i : 0);

Answered by Slai

Solution #4

You can easily convert a string array to an int array by using the following formula:

var converted = arr.Select(int.Parse)

Answered by A.Dara

Solution #5

var asIntegers = arr.Select(s => int.Parse(s)).ToArray(); 

You must ensure that you do not receive an IEnumerableint> as a response.

Answered by Rob

Post is based on https://stackoverflow.com/questions/1297231/convert-string-to-int-in-one-line-of-code-using-linq