What method in the String class returns only the first N characters

Question

I d like to write an extension method to the String class so that if the input string to is longer than the provided length N  only the first N characters are to be displayed   Here s how it looks like   public static string TruncateLongString this string str  int maxLength        if  str Length  lt   maxLength          return str      else           return the first maxLength characters                     What String     method can I use to get only the first N characters of str

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public static string TruncateLongString this string str  int maxLength        return str Length  lt   maxLength   str   str Remove maxLength

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string Substring 0 n      0 - start index and n - number of characters

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The  NET Substring method is fraught with peril  I developed extension methods that handle a wide variety of scenarios  The nice thing is it preserves the original behavior  but when you add an additional  true  parameter  it then resorts to the extension method to handle the exception  and returns the most logical values  based on the index and length  For example  if length is negative  and counts backward  You can look at the test results with wide variety of values on the fiddle at  https   dotnetfiddle net m1mSH9  This will give you a clear idea on how it resolves substrings   I always add these methods to all my projects  and never have to worry about code breaking  because something changed and the index is invalid  Below is the code        public static String Substring this String val  int startIndex  bool handleIndexException                if   handleIndexException              handleIndexException is false so call the base method             return val Substring startIndex                     if  string IsNullOrEmpty val                         return val                    return val Substring startIndex  lt  0   0   startIndex  gt   val Length - 1    val Length   startIndex              public static String Substring this String val  int startIndex  int length  bool handleIndexException                if   handleIndexException              handleIndexException is false so call the base method             return val Substring startIndex  length                     if  string IsNullOrEmpty val                         return val                    int newfrom  newlth  instrlength   val Length          if  length  lt  0    length is negative                       newfrom   startIndex   length              newlth   -1   length                    else   length is positive                       newfrom   startIndex              newlth   length                    if  newfrom   newlth  lt  0    newfrom  gt  instrlength - 1                        return string Empty                    if  newfrom  lt  0                        newlth   newfrom   newlth              newfrom   0                    return val Substring newfrom  Math Min newlth  instrlength - newfrom            I blogged about this back in May 2010 at  http   jagdale blogspot com 2010 05 substring-extension-method-that-does html

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Whenever I have to do string manipulations in C   I miss the good old Left and Right functions from Visual Basic  which are much simpler to use than Substring   So in most of my C  projects  I create extension methods for them   public static class StringExtensions       public static string Left this string str  int length                return str Substring 0  Math Min length  str Length               public static string Right this string str  int length                return str Substring str Length - Math Min length  str Length              Note  The Math Min part is there because Substring throws an ArgumentOutOfRangeException when the input string s length is smaller than the requested length  as already mentioned in some comments under previous answers   Usage   string longString    Long String       returns  Long   string left1   longString Left 4       returns  Long String   string left2   longString Left 100

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You can use LINQ str Take n  or str SubString 0  n   where the latter will throw an ArgumentOutOfRangeException exception for n  gt  str Length   Mind that the LINQ version returns a IEnumerable lt char gt   so you d have to convert the IEnumerable lt char gt  to string  new string s Take n  ToArray

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string truncatedToNLength   new string s Take n  ToArray         This solution has a tiny bonus in that if n is greater than s Length  it still does the right thing

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substring int startpos  int lenght

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Partially for the sake of summarization  excluding LINQ solution   here s two one-liners that address the int maxLength caveat of allowing negative values and also the case of null string    The Substring way  from Paul Ruane s answer     public static string Truncate this string s  uint maxLength    gt      s  Substring 0  Math Min s Length   int maxLength       The Remove way  from kbrimington s answer     public static string Truncate this string s  uint maxLength    gt      s  Length  gt  maxLength   s Remove  int maxLength    s

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if we are talking about validations also why we have not checked for null string entries  Any specific reasons   I think below way help since IsNullOrEmpty is a system defined method and ternary operators have cyclomatic complexity   1 while if      else    has value 2       public static string Truncate string input  int truncLength                return   String IsNullOrEmpty input   amp  amp  input Length  gt   truncLength                       input Substring 0  truncLength                       input

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Simply   public static String Truncate String input int maxLength       if input Length  gt  maxLength        return input Substring 0 maxLength      return input

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I added this in my project just because where I m using it is a high chance of it being used in loops  in a project hosted online hence I didn t want any crashes if I could manage it  The length fits a column I have  It s C 7  Just a one line    public static string SubStringN this string Message  int Len   499    gt   String IsNullOrEmpty Message     Message Length  gt   Len   Message Substring 0  Len    Message

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public static string TruncateLongString this string str  int maxLength        if  string IsNullOrEmpty str   return str       return str Substring 0  Math Min str Length  maxLength

[c#] What method in the String class returns only the first N characters?

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