How do I get the last four characters from a string in C

Question

Suppose I have a string    34234234d124    I want to get the last four characters of this string which is  d124   I can use SubString  but it needs a couple of lines of code  including naming a variable   Is it possible to get this result in one expression with C

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mystring Substring Math Max 0  mystring Length - 4      how many lines is this    If you re positive the length of your string is at least 4  then it s even shorter   mystring Substring mystring Length - 4

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This won t fail for any length string   string mystring    34234234d124   string last4   Regex Match mystring        5       Value     last4    d124  last4   Regex Match  d12         5       Value     last4    d12    This is probably overkill for the task at hand  but if there needs to be additional validation  it can possibly be added to the regular expression   Edit   I think this regex would be more efficient       4  Z

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Here is another alternative that shouldn t perform too badly  because of deferred execution    new string mystring Reverse   Take 4  Reverse   ToArray      Although an extension method for the purpose mystring Last 4  is clearly the cleanest solution  albeit a bit more work

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string var    quot 12345678 quot    var   var  4         var    quot 5678 quot

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Definition   public static string GetLast string source  int last         return last  gt   source Length   source   source Substring source Length - last       Usage   GetLast  string of   2     Result   of

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string var    12345678    if  var Length  gt   4        var   var substring var Length - 4  4        result    5678

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You can simply use Substring method of C   For ex   string str    1110000   string lastFourDigits   str Substring  str Length - 4   4     It will return result 0000

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All you have to do is    String result   mystring Substring mystring Length - 4

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I would like to extend the existing answer mentioning using new ranges in C  8 or higher  To make the code usable for all possible strings  If you want to copy code  I suggest example 5 or 6  string mystring   quot C  8 0 finally makes slicing possible quot    1  Slicing taking the end part- by specifying how many characters to omit from the beginning- this is  what VS 2019 suggests  string example1   mystring Math Max 0  mystring Length - 4        2  Slicing taking the end part- by specifying how many characters to take from the end  string example2   mystring  Math Min mystring Length  4        3  Slicing taking the end part- by replacing Max Min with the    operator  string example3    mystring length  gt  4   mystring  4      mystring     Personally  I like the second and third variant more than the first  MS doc reference for Indices and ranges  Null  But we are not done yet concerning universality  Every example so far will throw an exception for null strings  To consider null  if you don  t use non-nullable strings with C  8 or higher   and to do it without  if   classic example  with if  already given in another answer  we need  4  Slicing considering null- by specifying how many characters to omit  string example4   mystring  Math Max 0  mystring Length - 4        string Empty   5  Slicing considering null- by specifying how many characters to take  string example5   mystring   Math Min mystring Length  4        string Empty   6  Slicing considering null with the    operator  and two other     operators  -     You cannot put that in a whole in a string interpolation e g  for WriteLine   string example6    mystring  Length  gt  4    filePath  4      mystring    string Empty   7  Equivalent variant with good old Substring   for C  6 or 7 x   You cannot put that in a whole in a string interpolation e g  for WriteLine   string example7    mystring  Length  gt  4    mystring Substring mystring Length- 4    mystring    string Empty   Graceful degradation  I like the new features of C   Putting them on one line like in the last examples maybe looks a bit excessive  We ended up a little perl  ish didn  t we  But it  s a good example for learning and ok for me to use it once in a tested library method  Even better that we can get rid of null in modern C  if we want and avoid all this null-specific handling  Such a library extension method as a shortcut is really useful  Despite the advances in C  you have to write your own to get something easier to use than repeating the code above for every small string manipulation need  I am one of those who began with BASIC  and 40 years ago there was already Right      Funny  that it is possible to use Strings Right    from VB with C  still too as was shown in another answer  C  has chosen precision over graceful degradation  in opposite to old BASIC   So copy any appropriate variant you like in these answers and define a graceful shortcut function for yourself  mine is an extension function called RightChars int

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I threw together some code modified from various sources that will get the results you want  and do a lot more besides  I ve allowed for negative int values  int values that exceed the length of the string  and for end index being less than the start index  In that last case  the method returns a reverse-order substring  There are plenty of comments  but let me know if anything is unclear or just crazy  I was playing around with this to see what all I might use it for             lt summary gt          Returns characters slices from string between two indexes                   If start or end are negative  their indexes will be calculated counting          back from the end of the source string           If the end param is less than the start param  the Slice will return a          substring in reverse order                    lt param name  source  gt String the extension method will operate upon  lt  param gt           lt param name  startIndex  gt Starting index  may be negative  lt  param gt           lt param name  endIndex  gt Ending index  may be negative   lt  param gt           lt  summary gt      public static string Slice this string source  int startIndex  int endIndex   int MaxValue                   If startIndex or endIndex exceeds the length of the string they will be set             to zero if negative  or source Length if positive          if  source ExceedsLength startIndex   startIndex   startIndex  lt  0   0   source Length          if  source ExceedsLength endIndex   endIndex   endIndex  lt  0   0   source Length              Negative values count back from the end of the source string          if  startIndex  lt  0  startIndex   source Length   startIndex          if  endIndex  lt  0  endIndex   source Length   endIndex                       Calculate length of characters to slice from string          int length   Math Abs endIndex - startIndex              If the endIndex is less than the startIndex  return a reversed substring          if  endIndex  lt  startIndex  return source Substring endIndex  length  Reverse             return source Substring startIndex  length                   lt summary gt          Reverses character order in a string           lt  summary gt           lt param name  source  gt  lt  param gt           lt returns gt string lt  returns gt      public static string Reverse this string source                char   charArray   source ToCharArray            Array Reverse charArray           return new string charArray                   lt summary gt          Verifies that the index is within the range of the string source           lt  summary gt           lt param name  source  gt  lt  param gt           lt param name  index  gt  lt  param gt           lt returns gt bool lt  returns gt      public static bool ExceedsLength this string source  int index                return Math Abs index   gt  source Length   true   false          So if you have a string like  This is an extension method   here are some examples and results to expect   var s    This is an extension method      If you want to slice off end characters  just supply a negative startIndex value    but no endIndex value  or an endIndex value  gt   to the source string length   Console WriteLine s Slice -5       Returns  ethod   Console WriteLine s Slice -5  10       Results in a startIndex of 22  counting 5 back from the end      Since that is greater than the endIndex of 10  the result is reversed     Returns  m noisnetxe  Console WriteLine s Slice 2  15       Returns  is is an exte    Hopefully this version is helpful to someone  It operates just like normal if you don t use any negative numbers  and provides defaults for out of range params

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string mystring    34234234d124   mystring   mystring Substring mystring Length-4

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Using Substring is actually quite short and readable    var result   mystring Substring mystring Length - Math Min 4  mystring Length        result     d124

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Suggest using TakeLast method  for example  new String text TakeLast 4  ToArray

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Compared to some previous answers  the main difference is that this piece of code takes into consideration when the input string is    Null Longer than or matching the requested length Shorter than the requested length    Here it is   public static class StringExtensions       public static string Right this string str  int length                return str Substring str Length - length  length              public static string MyLast this string str  int length                if  str    null              return null          else if  str Length  gt   length              return str Substring str Length - length  length           else             return str

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You can use an extension method   public static class StringExtension       public static string GetLast this string source  int tail length               if tail length  gt   source Length            return source         return source Substring source Length - tail length             And then call   string mystring    34234234d124   string res   mystring GetLast 4

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Update 2020  C  8 0 finally makes this easy    gt   C  8 0 finally makes this easy   4     easy    You can also slice arrays in the same way  see Indices and ranges

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Use a generic Last lt T gt   That will work with ANY IEnumerable  including string   public static IEnumerable lt T gt  Last lt T gt  this IEnumerable lt T gt  enumerable  int nLastElements        int count   Math Min enumerable Count    nLastElements       for  int i   enumerable Count   - count  i  lt  enumerable Count    i                  yield return enumerable ElementAt i             And a specific one for string   public static string Right this string str  int nLastElements        return new string str Last nLastElements  ToArray

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assuming you wanted the strings in between a string which is located 10 characters from the last character and you need only 3 characters   Let s say StreamSelected    rtsp   72 142 0 230 80 SMIL-CHAN-273 4CIF-273 stream   In the above  I need to extract the  273  that I will use in database query            find the length of the string                     int streamLen StreamSelected Length             now remove all characters except the last 10 characters         string streamLessTen   StreamSelected Remove 0  streamLen - 10                  extract the 3 characters using substring starting from index 0           show Result is a TextBox  txtStreamSubs  with          txtStreamSubs Text   streamLessTen Substring 0  3

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It is just this   int count   4  string sub   mystring Substring mystring Length - count  count

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mystring   mystring Length  gt  4   mystring Substring mystring Length - 4  4    mystring

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Ok  so I see this is an old post  but why are we rewriting code that is already provided in the framework    I would suggest that you add a reference to the framework DLL  Microsoft VisualBasic   using Microsoft VisualBasic         string value   Strings Right  34234234d124   4

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A simple solution would be   string mystring    34234234d124   string last4   mystring Substring mystring Length - 4  4

[c#] How do I get the last four characters from a string in C#?

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