Example. Here we see a method that deals with char arrays and the new string constructor. When you need to build a string char-by-char, you should use a char array for best performance.
using System;
class Program
{
public static string CharCombine(char c0, char c1, char c2, char c3)
{
// Allocate an array, and assign its elements to the arguments, then convert to a string.
char[] array = new char[4];
array[0] = c0;
array[1] = c1;
array[2] = c2;
array[3] = c3;
return new string(array);
}
static void Main()
{
char a = 'a';
char b = 'b';
char c = 'c';
char d = 'd';
char e = 'e';
// Use CharCombine method.
Console.WriteLine(CharCombine(a, b, c, d));
Console.WriteLine(CharCombine(b, c, d, e));
}
}abcd
bcde
Benchmark. What is the fastest way to convert multiple chars to a string? This benchmark will help us learn the answer to this question. The CharCombine() method is faster.
Version 1 Here we call CharCombine() with 4 arguments in a tight loop. We ensure the returned strings are valid.
Version 2 The alternative here is the string.Concat method, which you can use with "+" between the chars with ToString().
Result In .NET 8, using a char array to combine multiple chars into a string is significantly faster.
using System;
using System.Diagnostics;
class Program
{
public static string CharCombine(char c0, char c1, char c2, char c3)
{
char[] array = new char[4];
array[0] = c0;
array[1] = c1;
array[2] = c2;
array[3] = c3;
return new string(array);
}
public static void Main()
{
char a = 'a';
char b = 'b';
char c = 'c';
char d = 'd';
const int _max = 1000000;
var s1 = Stopwatch.StartNew();
// Version 1: combine chars with char array.
for (int i = 0; i < _max; i++)
{
string v1 = CharCombine(a, b, c, d);
string v2 = CharCombine(d, c, b, a);
if (v1 != "abcd" || v2 != "dcba") {
return;
}
}
s1.Stop();
var s2 = Stopwatch.StartNew();
// Version 2: use ToString and concatenation.
for (int i = 0; i < _max; i++)
{
string v1 = a.ToString() + b.ToString() + c.ToString() + d.ToString();
string v2 = d.ToString() + c.ToString() + b.ToString() + a.ToString();
if (v1 != "abcd" || v2 != "dcba") {
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"));
}
}22.27 ns CharCombine
60.78 ns +
Summary. We allocated a char array as a buffer to store 4 chars. You can easily adapt the method to handle two, three, five, or even more chars, and it will likely perform well.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Dec 3, 2023 (new example).
