Fastest way to remove first char in a String

Question

Say we have the following string   string data    temp string     If we want to remove the first character   we can do by a lot of ways such as    data Remove 0 1   data TrimStart       data Substring 1     But  really I don t know which one has the best algorithm and doing that faster     Is there a one that is the best or all are the same

User · Accepted Answer

The second option really isn t the same as the others - if the string is     foo  it will become  foo  instead of    foo    The first option needs a bit more work to understand than the third - I would view the Substring option as the most common and readable    Obviously each of them as an individual statement won t do anything useful - you ll need to assign the result to a variable  possibly data itself    I wouldn t take performance into consideration here unless it was actually becoming a problem for you - in which case the only way you d know would be to have test cases  and then it s easy to just run those test cases for each option and compare the results  I d expect Substring to probably be the fastest here  simply because Substring always ends up creating a string from a single chunk of the original input  whereas Remove has to at least potentially glue together a start chunk and an end chunk

User · Answer

You could profile it  if you really cared  Write a loop of many iterations and see what happens  Chances are  however  that this is not the bottleneck in your application  and TrimStart seems the most semantically correct  Strive to write code readably before optimizing

User · Answer

I know this is hyper-optimization land  but it seemed like a good excuse to kick the wheels of BenchmarkDotNet  The result of this test  on  NET Core even  is that Substring is ever so slightly faster than Remove  in this sample test   19 37ns vs 22 52ns for Remove  So some  16  faster   using System  using BenchmarkDotNet Attributes   namespace BenchmarkFun       public class StringSubstringVsRemove               public readonly string SampleString     My name is Daffy Duck              Benchmark          public string StringSubstring     gt  SampleString Substring 1             Benchmark          public string StringRemove     gt  SampleString Remove 0  1            public void AssertTestIsValid                         string subsRes   StringSubstring                string remvRes   StringRemove                 if  subsRes    null                    subsRes Length    SampleString Length - 1                    subsRes    remvRes                    throw new Exception  INVALID TEST                                        class Program               static void Main                            let s make sure test results are really equal   valid             new StringSubstringVsRemove   AssertTestIsValid                 var summary   BenchmarkRunner Run lt StringSubstringVsRemove gt                         Results   BenchmarkDotNet v0 11 4  OS Windows 10 0 17763 253  1809 October2018Update Redstone5  Intel Core i7-6700HQ CPU 2 60GHz  Skylake   1 CPU  8 logical and 4 physical cores  NET Core SDK 3 0 100-preview-010184    Host         NET Core 3 0 0-preview-27324-5  CoreCLR 4 6 27322 0  CoreFX 4 7 19 7311   64bit RyuJIT   DefaultJob    NET Core 3 0 0-preview-27324-5  CoreCLR 4 6 27322 0  CoreFX 4 7 19 7311   64bit RyuJIT             Method       Mean       Error      StdDev    ----------------  ---------  ----------  ----------     StringSubstring   19 37 ns   0 3940 ns   0 3493 ns        StringRemove   22 52 ns   0 4062 ns   0 3601 ns

User · Answer

I d guess that Remove and Substring would tie for first place  since they both slurp up a fixed-size portion of the string  whereas TrimStart does a scan from the left with a test on each character and then has to perform exactly the same work as the other two methods  Seriously  though  this is splitting hairs

User · Answer

I would just use string data   quot  temp string quot   data   data substring 1   Output  temp string That always works for me

[c#] Fastest way to remove first char in a String

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