StringBuilder performance in C#?
c#
Solution
The first will be more efficient. The compiler will convert it to the following single call:
StringBuilder sb = new StringBuilder();
sb.Append("HelloHowareyou");
Measuring the performance
The best way to know which is faster is to measure it. I'll get straight to the point: here are the results (smaller times means faster):
sb.Append("Hello" + "How" + "are" + "you") : 11.428s
sb.Append("Hello").Append("How").Append("are").Append("you"): 15.314s
sb.Append(a + b + c + d) : 21.970s
sb.Append(a).Append(b).Append(c).Append(d) : 15.529s
The number given is the number of seconds to perform the operation 100 million times in a tight loop.
Conclusions
- The fastest is using string literals and `+`.
- But if you have variables, using `Append` is faster than `+`. The first version is slower because of an extra call to `String.Concat`.
In case you want to test this yourself, here's the program I used to get the above timings:
using System;
using System.Text;
public class Program
{
public static void Main()
{
DateTime start, end;
int numberOfIterations = 100000000;
start = DateTime.UtcNow;
for (int i = 0; i < numberOfIterations; ++i)
{
StringBuilder sb = new StringBuilder();
sb.Append("Hello" + "How" + "are" + "you");
}
end = DateTime.UtcNow;
DisplayResult("sb.Append(\"Hello\" + \"How\" + \"are\" + \"you\")", start, end);
start = DateTime.UtcNow;
for (int i = 0; i < numberOfIterations; ++i)
{
StringBuilder sb = new StringBuilder();
sb.Append("Hello").Append("How").Append("are").Append("you");
}
end = DateTime.UtcNow;
DisplayResult("sb.Append(\"Hello\").Append(\"How\").Append(\"are\").Append(\"you\")", start, end);
string a = "Hello";
string b = "How";
string c = "are";
string d = "you";
start = DateTime.UtcNow;
for (int i = 0; i < numberOfIterations; ++i)
{
StringBuilder sb = new StringBuilder();
sb.Append(a + b + c + d);
}
end = DateTime.UtcNow;
DisplayResult("sb.Append(a + b + c + d)", start, end);
start = DateTime.UtcNow;
for (int i = 0; i < numberOfIterations; ++i)
{
StringBuilder sb = new StringBuilder();
sb.Append(a).Append(b).Append(c).Append(d);
}
end = DateTime.UtcNow;
DisplayResult("sb.Append(a).Append(b).Append(c).Append(d)", start, end);
Console.ReadLine();
}
private static void DisplayResult(string name, DateTime start, DateTime end)
{
Console.WriteLine("{0,-60}: {1,6:0.000}s", name, (end - start).TotalSeconds);
}
}
Problem
I have a `StringBuilder` object where I am adding some strings like follows: I want to know which one is better approach here, first one is this: ``` StringBuilder sb = new StringBuilder(); sb.Append("Hello" + "How" + "are" + "you"); ``` and the second one is: ``` StringBuilder sb = new StringBuilder(); sb.Append("Hello").Append("How").Append("are").Append("you"); ```