koobas.hobune.stream
Access all Items in an Array
Hello everyone,
I need to be able to turn a bunch of strings in an array into 1 string (with commas in between each entry). I guess pseudocode would look like:
void Update ()
{
string newString = Array [1] + "," + Array [2] + "," + Array [3] etc
}
But I need to automate this, as I don't want to write out above for 200 array entries or so. Any ideas? Thanks, Wolfshadow
Use a for/foreach loop
string newString = "";
foreach(string s in array)
{
newString += s + ",";
}
This will work, but if you need to do it often it will effect performance. The solution is to use a stringbuilder like so:
using System.Text;
StringBuilder sb = new StringBuilder();
foreach(string s in array)
{
sb.append(s);
}
string newString = sb.ToString();
Using Linq is best for this scenario. According to @bobisgod234 result will be same but result will iterate in all the array and return PreviousString+Currentsting. According to @Arycama Code will work fine but performance will slow because StringBuilder creates instance and then apply iteration.
using System.Linq;
using UnityEngine;
public class ArrayTest : $$anonymous$$onoBehaviour
{
[SerializeField] private string[] _stringArray;
void Start()
{
string newString = _stringArray.Aggregate<string, string>(null, (current, item) => current + item);
Debug.Log(newString);
}
}
Is there really a measurable performance difference between stringbuilder and aggregate? StringBuilder looks so much cleaner in my opinion, and I believe Aggregate is going to generate a new copy of the string each time it appends two strings together.
Aggregate() uses a loop but sb.append(s) uses Select(), which in turn uses an iterator. And using an iterator means there is some overhead: creating the iterator object and (probably more importantly) one more method invocation for each item.
Use an extension method. Here is mine:
using System.Linq;
// string join that works on any enumerable
public static class UtilExtensions {
public static string Join<T>(this IEnumerable<T> values, string delim = ",") {
return String.Join(delim, values.Select(v => v == null ? "null" : v.ToString()).ToArray());
}
}
void Update () {
string newString = SomeArray.Join();
}
This code works and it is idiomatic C#. Study it, and when you understand it, use it everywhere. I do.
Look up "for" loops.
https://unity3d.com/learn/tutorials/topics/scripting/loops
Make a loop that lasts as long as your array length, and then you add each array entry to your string variable.
There is the Join method on System.String for specificailly this purpose:
public static string Join(
string separator,
params string[] value
)
https://msdn.microsoft.com/en-us/library/57a79xd0(v=vs.110).aspx
No need for loops or Linq and almost certainly faster. See this question from stackoverflow: http://stackoverflow.com/questions/585860/string-join-vs-stringbuilder-which-is-faster
$$anonymous$$y solution does use String.Join(). The reason for wrapping it in Linq is to make it easier to use with a default delimiter, works on any object not just strings, handles nulls, works on any IEnumerable.
What's not to like?
BTW the Linq overhead is small -- check the source code or benchmark it.
