ToCharArray

This C# method converts strings to character arrays. It is called on a string and returns a new char array. The original string is left unchanged.

It is possible to manipulate a char array in-place, which we cannot do with a string. This makes many performance optimizations possible.

Example

First we use ToCharArray() to get a character array from the contents of a string. The example uses an input string, and then assigns a char array to the result of ToCharArray.

using System;

// Input string.
string value = "abcd";

// Use ToCharArray to convert string to array.
char[] array = value.ToCharArray();

// Loop through array.
for (int i = 0; i < array.Length; i++)
{
    // Get character from array.
    char letter = array[i];
    // Display each letter.
    Console.Write("Letter: ");
    Console.WriteLine(letter);
}
Letter: a
Letter: b
Letter: c
Letter: d

Benchmark, ToCharArray

Here we measure the performance of ToCharArray. We copy a string to a char array with 2 versions of C# code.

using System;
using System.Diagnostics;

const int _max = 2000000;
// Create 500-char string.
string text = new string('P', 500);
// Version 1: use ToCharArray.
var s1 = Stopwatch.StartNew();
for (int i = 0; i < _max; i++)
{
    char[] result = text.ToCharArray();
    if (result[0] != 'P')
    {
        return;
    }
}
s1.Stop();
// Version 2: copy chars from string with loop.
var s2 = Stopwatch.StartNew();
for (int i = 0; i < _max; i++)
{
    char[] result = new char[text.Length];
    for (int v = 0; v < text.Length; v++)
    {
        result[v] = text[v];
    }
    if (result[0] != 'P')
    {
        return;
    }
}
s2.Stop();
Console.WriteLine(((double)(s1.Elapsed.TotalMilliseconds * 1000000) / _max).ToString("0.00 ns"));
Console.WriteLine(((double)(s2.Elapsed.TotalMilliseconds * 1000000) / _max).ToString("0.00 ns"));
 68.30 ns    ToCharArray
323.36 ns    new char[], for loop

Uses

With ToCharArray, the char array you receive is mutable. You can change characters. The method is ideal for transforming chars (like in ROT13, or uppercasing the first letter).

ToCharArray is often useful: it returns a character array filled with the string's characters. We can modify this array in-place—this improves the performance of code.