Example. Here we see an optimization that deals with char arrays and the new string constructor. My other work shows that when you need to build a string char-by-char, you should use a char array for best performance.
Char ArrayCharCombine: We call this method by passing it 4 chars. We can adapt the code to be used on any number of chars.
Tip: It is contained in a static class and is a static method, which is ideal for a utility method such as this. It does not save state.
StaticInfo: CharCombine allocates a new char array with 4 elements. Then, it assigns slots at indices 0 to 3 to the four parameter chars.
Finally: The new string(char[]) constructor is invoked in the return statement, which builds the string from the char buffer we created.
String ConstructorReturn C# program that combines four chars
using System;
class CharTool
{
/// <summary>
/// Combine four chars.
/// </summary>
public static string CharCombine(char c0, char c1, char c2, char c3)
{
// Combine chars into array
char[] arr = new char[4];
arr[0] = c0;
arr[1] = c1;
arr[2] = c2;
arr[3] = c3;
// Return new string key
return new string(arr);
}
}
class Program
{
static void Main()
{
char a = 'a';
char b = 'b';
char c = 'c';
char d = 'd';
char e = 'e';
// Use CharCombine method
Console.WriteLine(CharTool.CharCombine(a, b, c, d));
Console.WriteLine(CharTool.CharCombine(b, c, d, e));
}
}
Output
abcd
bcde
Benchmark. The alternative here is the string.Concat method, which you can use with "+" between the four chars with ToString(). It is much slower and does unnecessary things. Performance figures are shown.
Varibles used in benchmarks: C#
char a = 'a';
char b = 'b';
char c = 'c';
char d = 'd';
Code benchmarked in loops: C#
// Custom method
string s1 = CharTool.CharCombine(a, b, c, d); // [above]
string s2 = CharTool.CharCombine(d, c, b, a);
// Concatenation
string s1 = a.ToString() + b.ToString() + c.ToString() + d.ToString();
string s2 = d.ToString() + c.ToString() + b.ToString() + a.ToString();
Combine chars benchmarks:
CharCombine method: 520 ms
Char concat: 1887 ms
Summary. We allocated a char array as a buffer to store four chars. You can easily adapt the method to handle two, three, five, or even more chars, and it will likely perform well. We should be careful with the params keyword.
