C - Simplest way to remove first occurrence of a substring from another string

Question

I need to remove the first  and ONLY the first  occurrence of a string from another string   Here is an example replacing the string    Iteration    This    ProjectName  Iteration  Release1  Iteration1   would become this    ProjectName  Release1  Iteration1   Here some code that does this   const string removeString      Iteration   int index   sourceString IndexOf removeString   int length   removeString Length  String startOfString   sourceString Substring 0  index   String endOfString   sourceString Substring index   length   String cleanPath   startOfString   endOfString    That seems like a lot of code     So my question is this   Is there a cleaner more readable more concise way to do this

User · Answer

string myString   sourceString Remove sourceString IndexOf removeString  removeString Length     EDIT   OregonGhost is right  I myself would break the script up with conditionals to check for such an occurence  but I was operating under the assumption that the strings were given to belong to each other by some requirement  It is possible that business-required exception handling rules are expected to catch this possibility  I myself would use a couple of extra lines to perform conditional checks and also to make it a little more readable for junior developers who may not take the time to read it thoroughly enough

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You could use an extension method for fun  Typically I don t recommend attaching extension methods to such a general purpose class like string  but like I said this is fun  I borrowed  Luke s answer since there is no point in re-inventing the wheel    Test  public void Should remove first occurrance of string          var source    ProjectName  Iteration  Release1  Iteration1        Assert That          source RemoveFirst    Iteration            Is EqualTo  ProjectName  Release1  Iteration1        public static class StringExtensions       public static string RemoveFirst this string source  string remove            int index   source IndexOf remove           return  index  lt  0                source               source Remove index  remove Length

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I definitely agree that this is perfect for an extension method  but I think it can be improved a bit   public static string Remove this string source  string remove   int firstN                if firstN  lt   0    string IsNullOrEmpty source     string IsNullOrEmpty remove                         return source                    int index   source IndexOf remove           return index  lt  0   source   source Remove index  remove Length  Remove remove  --firstN           This does a bit of recursion which is always fun   Here is a simple unit test as well       TestMethod        public void RemoveTwiceTest                 string source    look up look up look it up           string remove    look           int firstN   2          string expected     up  up look it up           string actual          actual   source Remove remove  firstN           Assert AreEqual expected  actual

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If you d like a simple method to resolve this problem   Can be used as an extension   See below        public static string RemoveFirstInstanceOfString this string value  string removeString                int index   value IndexOf removeString  StringComparison Ordinal           return index  lt  0   value   value Remove index  removeString Length           Usage        string valueWithPipes      1   2   3       string valueWithoutFirstpipe   valueWithPipes RemoveFirstInstanceOfString             Output  valueWithoutFirstpipe     1   2   3     Inspired by and modified  LukeH s and  Mike s answer   Don t forget the StringComparison Ordinal to prevent issues with Culture settings  https   www jetbrains com help resharper 2018 2 StringIndexOfIsCultureSpecific 1 html

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int index   sourceString IndexOf removeString   string cleanPath    index  lt  0        sourceString       sourceString Remove index  removeString Length

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Wrote a quick TDD Test for this       TestMethod      public void Test                 var input     ProjectName Iteration Release1 Iteration1           var pattern       Iteration            var rgx   new Regex pattern           var result   rgx Replace input      1            Assert IsTrue result Equals   ProjectName Release1 Iteration1             rgx Replace input      1   says to look in input for anything matching the pattern  with     1 time

User · Answer

sourceString Replace removeString

[c#] C# - Simplest way to remove first occurrence of a substring from another string

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