Remove element of a regular array

Question

I have an array of Foo objects  How do I remove the second element of the array   I need something similar to RemoveAt   but for a regular array

User · Answer

The nature of arrays is that their length is immutable. You can't add or delete any of the array items.

You will have to create a new array that is one element shorter and copy the old items to the new array, excluding the element you want to delete.

So it is probably better to use a List instead of an array.

User · Answer

I use this method for removing an element from an object array   In my situation  my arrays are small in length   So if you have large arrays you may need another solution   private int   RemoveIndices int   IndicesArray  int RemoveAt        int   newIndicesArray   new int IndicesArray Length - 1        int i   0      int j   0      while  i  lt  IndicesArray Length                if  i    RemoveAt                        newIndicesArray j    IndicesArray i               j                       i               return newIndicesArray

User · Answer

As usual  I m late to the party     I d like to add another option to the nice solutions list already present      I would see this as a good opportunity for Extensions   Reference  http   msdn microsoft com en-us library bb311042 aspx   So  we define some static class and in it  our Method  After that  we can use our extended method willy-nilly       using System   namespace FunctionTesting           The class doesn t matter  as long as it s static     public static class SomeRandomClassWhoseNameDoesntMatter               Here s the actual method that extends arrays         public static T   RemoveAt lt T gt   this T   oArray  int idx                 T   nArray   new T oArray Length - 1               for  int i   0  i  lt  nArray Length    i                     nArray i      i  lt  idx     oArray i    oArray i   1                             return nArray                          Sample usage        class Program           static void Main  string   args                 string   myStrArray      Zero    One    Two    Three                 Console WriteLine  String Join       myStrArray                  myStrArray   myStrArray RemoveAt  2                Console WriteLine  String Join       myStrArray                     Output                 Zero One Two Three                  Zero One Three                               int   myIntArray     0  1  2  3                Console WriteLine  String Join       myIntArray                  myIntArray   myIntArray RemoveAt  2                Console WriteLine  String Join       myIntArray                     Output                 0 1 2 3                  0 1 3

User · Answer

Not exactly the way to go about this  but if the situation is trivial and you value your time  you can try this for nullable types    Foos index    null   and later check for null entries in your logic

User · Answer

Here s a small collection of helper methods I produced based on some of the existing answers  It utilizes both extensions and static methods with reference parameters for maximum idealness   public static class Arr       public static int IndexOf lt TElement gt  this TElement   Source  TElement Element                for  var i   0  i  lt  Source Length  i                          if  Source i  Equals Element                   return i                     return -1             public static TElement   Add lt TElement gt  ref TElement   Source  params TElement   Elements                var OldLength   Source Length          Array Resize ref Source  OldLength   Elements Length            for  int j   0  Count   Elements Length  j  lt  Count  j                Source OldLength   j    Elements j            return Source             public static TElement   New lt TElement gt  params TElement   Elements                return Elements    new TElement 0              public static void Remove lt TElement gt  ref TElement   Source  params TElement   Elements                foreach  var i in Elements              RemoveAt ref Source  Source IndexOf i               public static void RemoveAt lt TElement gt  ref TElement   Source  int Index                var Result   new TElement Source Length - 1            if  Index  gt  0              Array Copy Source  0  Result  0  Index            if  Index  lt  Source Length - 1              Array Copy Source  Index   1  Result  Index  Source Length - Index - 1            Source   Result            Performance wise  it is decent  but it could probably be improved  Remove relies on IndexOf and a new array is created for each element you wish to remove by calling RemoveAt   IndexOf is the only extension method as it does not need to return the original array  New accepts multiple elements of some type to produce a new array of said type  All other methods must accept the original array as a reference so there is no need to assign the result afterward as that happens internally already   I would ve defined a Merge method for merging two arrays  however  that can already be accomplished with Add method by passing in an actual array versus multiple  individual elements  Therefore  Add may be used in the following two ways to join two sets of elements   Arr Add lt string gt  ref myArray   A    B    C      Or   Arr Add lt string gt  ref myArray  anotherArray

User · Answer

I use this method for removing an element from an object array   In my situation  my arrays are small in length   So if you have large arrays you may need another solution   private int   RemoveIndices int   IndicesArray  int RemoveAt        int   newIndicesArray   new int IndicesArray Length - 1        int i   0      int j   0      while  i  lt  IndicesArray Length                if  i    RemoveAt                        newIndicesArray j    IndicesArray i               j                       i               return newIndicesArray

User · Answer

Here s how I did it         public static ElementDefinitionImpl   RemoveElementDefAt          ElementDefinition   oldList          int removeIndex                     ElementDefinitionImpl   newElementDefList   new ElementDefinitionImpl  oldList Length - 1             int offset   0          for   int index   0  index  lt  oldList Length  index                           ElementDefinitionImpl elementDef   oldList  index   as ElementDefinitionImpl              if   index    removeIndex                                     This is the one we want to remove  so we won t copy it   But                      every subsequent elementDef will by shifted down by one                  offset   -1                            else                               newElementDefList  index   offset     elementDef                                  return newElementDefList

User · Answer

LINQ one-line solution   myArray   myArray Where  source  index    gt  index    1  ToArray      The 1 in that example is the index of the element to remove -- in this example  per the original question  the 2nd element  with 1 being the second element in C  zero-based array indexing    A more complete example   string   myArray      a    b    c    d    e     int indexToRemove   1  myArray   myArray Where  source  index    gt  index    indexToRemove  ToArray      After running that snippet  the value of myArray will be    a    c    d    e

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private int   removeFromArray int   array  int id                int difference   0  currentValue 0            get new Array length         for  int i 0  i lt array Length  i                          if  array i   id                                difference    1                                    create new array         int   newArray   new int array Length-difference           for  int i   0  i  lt  array Length  i                           if  array i     id                                newArray currentValue    array i                   currentValue    1                                   return newArray

User · Answer

I know this article is ten years old and therefore probably dead  but here s what I d try doing   Use the IEnumerable Skip   method  found in System Linq  It will skip the selected element from the array  and return another copy of the array that only contains everything except the selected object  Then just repeat that for every element you want removed and after that save it to a variable    For example  if we have an array named  Sample   of type int    with 5 numbers  We want to remove the 2nd one  so trying  Sample Skip 2    should return the same array except without the 2nd number

User · Answer

The nature of arrays is that their length is immutable. You can't add or delete any of the array items.

You will have to create a new array that is one element shorter and copy the old items to the new array, excluding the element you want to delete.

So it is probably better to use a List instead of an array.

User · Answer

Here is an old version I have that works on version 1 0 of the  NET framework and does not need generic types   public static Array RemoveAt Array source  int index        if  source    null          throw new ArgumentNullException  source         if  0  gt  index    index  gt   source Length          throw new ArgumentOutOfRangeException  index   index   index is outside the bounds of source array         Array dest   Array CreateInstance source GetType   GetElementType    source Length - 1       Array Copy source  0  dest  0  index       Array Copy source  index   1  dest  index  source Length - index - 1        return dest      This is used like this   class Program       static void Main string   args                string   x   new string 20           for  int i   0  i  lt  x Length  i                x i     i 1  ToString             string   y    string   MyArrayFunctions RemoveAt x  3            for  int i   0  i  lt  y Length  i                Console WriteLine y i

User · Answer

Here is an old version I have that works on version 1 0 of the  NET framework and does not need generic types   public static Array RemoveAt Array source  int index        if  source    null          throw new ArgumentNullException  source         if  0  gt  index    index  gt   source Length          throw new ArgumentOutOfRangeException  index   index   index is outside the bounds of source array         Array dest   Array CreateInstance source GetType   GetElementType    source Length - 1       Array Copy source  0  dest  0  index       Array Copy source  index   1  dest  index  source Length - index - 1        return dest      This is used like this   class Program       static void Main string   args                string   x   new string 20           for  int i   0  i  lt  x Length  i                x i     i 1  ToString             string   y    string   MyArrayFunctions RemoveAt x  3            for  int i   0  i  lt  y Length  i                Console WriteLine y i

User · Answer

Not exactly the way to go about this  but if the situation is trivial and you value your time  you can try this for nullable types    Foos index    null   and later check for null entries in your logic

User · Answer

private int   removeFromArray int   array  int id                int difference   0  currentValue 0            get new Array length         for  int i 0  i lt array Length  i                          if  array i   id                                difference    1                                    create new array         int   newArray   new int array Length-difference           for  int i   0  i  lt  array Length  i                           if  array i     id                                newArray currentValue    array i                   currentValue    1                                   return newArray

User · Answer

This is a way to delete an array element  as of  Net 3 5  without copying to another array - using the same array instance with Array Resize lt T gt    public static void RemoveAt lt T gt  ref T   arr  int index        for  int a   index  a  lt  arr Length - 1  a                     moving elements downwards  to fill the gap at  index          arr a    arr a   1                finally  let s decrement Array s size by one     Array Resize ref arr  arr Length - 1

User · Answer

As usual  I m late to the party     I d like to add another option to the nice solutions list already present      I would see this as a good opportunity for Extensions   Reference  http   msdn microsoft com en-us library bb311042 aspx   So  we define some static class and in it  our Method  After that  we can use our extended method willy-nilly       using System   namespace FunctionTesting           The class doesn t matter  as long as it s static     public static class SomeRandomClassWhoseNameDoesntMatter               Here s the actual method that extends arrays         public static T   RemoveAt lt T gt   this T   oArray  int idx                 T   nArray   new T oArray Length - 1               for  int i   0  i  lt  nArray Length    i                     nArray i      i  lt  idx     oArray i    oArray i   1                             return nArray                          Sample usage        class Program           static void Main  string   args                 string   myStrArray      Zero    One    Two    Three                 Console WriteLine  String Join       myStrArray                  myStrArray   myStrArray RemoveAt  2                Console WriteLine  String Join       myStrArray                     Output                 Zero One Two Three                  Zero One Three                               int   myIntArray     0  1  2  3                Console WriteLine  String Join       myIntArray                  myIntArray   myIntArray RemoveAt  2                Console WriteLine  String Join       myIntArray                     Output                 0 1 2 3                  0 1 3

User · Answer

This is a way to delete an array element  as of  Net 3 5  without copying to another array - using the same array instance with Array Resize lt T gt    public static void RemoveAt lt T gt  ref T   arr  int index        for  int a   index  a  lt  arr Length - 1  a                     moving elements downwards  to fill the gap at  index          arr a    arr a   1                finally  let s decrement Array s size by one     Array Resize ref arr  arr Length - 1

User · Answer

Here s a small collection of helper methods I produced based on some of the existing answers  It utilizes both extensions and static methods with reference parameters for maximum idealness   public static class Arr       public static int IndexOf lt TElement gt  this TElement   Source  TElement Element                for  var i   0  i  lt  Source Length  i                          if  Source i  Equals Element                   return i                     return -1             public static TElement   Add lt TElement gt  ref TElement   Source  params TElement   Elements                var OldLength   Source Length          Array Resize ref Source  OldLength   Elements Length            for  int j   0  Count   Elements Length  j  lt  Count  j                Source OldLength   j    Elements j            return Source             public static TElement   New lt TElement gt  params TElement   Elements                return Elements    new TElement 0              public static void Remove lt TElement gt  ref TElement   Source  params TElement   Elements                foreach  var i in Elements              RemoveAt ref Source  Source IndexOf i               public static void RemoveAt lt TElement gt  ref TElement   Source  int Index                var Result   new TElement Source Length - 1            if  Index  gt  0              Array Copy Source  0  Result  0  Index            if  Index  lt  Source Length - 1              Array Copy Source  Index   1  Result  Index  Source Length - Index - 1            Source   Result            Performance wise  it is decent  but it could probably be improved  Remove relies on IndexOf and a new array is created for each element you wish to remove by calling RemoveAt   IndexOf is the only extension method as it does not need to return the original array  New accepts multiple elements of some type to produce a new array of said type  All other methods must accept the original array as a reference so there is no need to assign the result afterward as that happens internally already   I would ve defined a Merge method for merging two arrays  however  that can already be accomplished with Add method by passing in an actual array versus multiple  individual elements  Therefore  Add may be used in the following two ways to join two sets of elements   Arr Add lt string gt  ref myArray   A    B    C      Or   Arr Add lt string gt  ref myArray  anotherArray

User · Answer

In a normal array you have to shuffle down all the array entries above 2 and then resize it using the Resize method  You might be better off using an ArrayList

User · Answer

Here s how I did it         public static ElementDefinitionImpl   RemoveElementDefAt          ElementDefinition   oldList          int removeIndex                     ElementDefinitionImpl   newElementDefList   new ElementDefinitionImpl  oldList Length - 1             int offset   0          for   int index   0  index  lt  oldList Length  index                           ElementDefinitionImpl elementDef   oldList  index   as ElementDefinitionImpl              if   index    removeIndex                                     This is the one we want to remove  so we won t copy it   But                      every subsequent elementDef will by shifted down by one                  offset   -1                            else                               newElementDefList  index   offset     elementDef                                  return newElementDefList

User · Answer

LINQ one-line solution   myArray   myArray Where  source  index    gt  index    1  ToArray      The 1 in that example is the index of the element to remove -- in this example  per the original question  the 2nd element  with 1 being the second element in C  zero-based array indexing    A more complete example   string   myArray      a    b    c    d    e     int indexToRemove   1  myArray   myArray Where  source  index    gt  index    indexToRemove  ToArray      After running that snippet  the value of myArray will be    a    c    d    e

User · Answer

I know this article is ten years old and therefore probably dead  but here s what I d try doing   Use the IEnumerable Skip   method  found in System Linq  It will skip the selected element from the array  and return another copy of the array that only contains everything except the selected object  Then just repeat that for every element you want removed and after that save it to a variable    For example  if we have an array named  Sample   of type int    with 5 numbers  We want to remove the 2nd one  so trying  Sample Skip 2    should return the same array except without the 2nd number

User · Answer

The nature of arrays is that their length is immutable. You can't add or delete any of the array items.

You will have to create a new array that is one element shorter and copy the old items to the new array, excluding the element you want to delete.

So it is probably better to use a List instead of an array.

User · Answer

First step You need to convert the array into a list  you could write an extension method like this      Convert An array of string  to a list of string public static List lt string gt  ConnvertArrayToList this string    array            DECLARE a list of string and add all element of the array into it      List lt string gt  myList   new List lt string gt         foreach  string s in array           myList Add s             return myList       Second step Write an extension method to convert back the list into an array     convert a list of string to an array  public static string   ConvertListToArray this List lt string gt  list         string   array   new string list Capacity       array   list Select i   gt  i ToString    ToArray        return array      Last steps Write your final method  but remember to remove the element at index before converting back to an array like the code show  public static string   removeAt string   array  int index         List lt string gt  myList   array ConnvertArrayToList        myList RemoveAt index       return myList ConvertListToArray         examples codes could be find on my blog  keep tracking

User · Answer

The nature of arrays is that their length is immutable. You can't add or delete any of the array items.

You will have to create a new array that is one element shorter and copy the old items to the new array, excluding the element you want to delete.

So it is probably better to use a List instead of an array.

User · Answer

Try below code   myArray   myArray Where s   gt   myArray IndexOf s     indexValue   ToArray      or  myArray   myArray Where s   gt   s     not this    ToArray

User · Answer

If you don t want to use List   var foos   new List lt Foo gt  array   foos RemoveAt index   return foos ToArray      You could try this extension method that I haven t actually tested   public static T   RemoveAt lt T gt  this T   source  int index        T   dest   new T source Length - 1       if  index  gt  0           Array Copy source  0  dest  0  index        if  index  lt  source Length - 1           Array Copy source  index   1  dest  index  source Length - index - 1        return dest      And use it like   Foo   bar   GetFoos    bar   bar RemoveAt 2

User · Answer

If you don t want to use List   var foos   new List lt Foo gt  array   foos RemoveAt index   return foos ToArray      You could try this extension method that I haven t actually tested   public static T   RemoveAt lt T gt  this T   source  int index        T   dest   new T source Length - 1       if  index  gt  0           Array Copy source  0  dest  0  index        if  index  lt  source Length - 1           Array Copy source  index   1  dest  index  source Length - index - 1        return dest      And use it like   Foo   bar   GetFoos    bar   bar RemoveAt 2

User · Answer

In a normal array you have to shuffle down all the array entries above 2 and then resize it using the Resize method  You might be better off using an ArrayList

User · Answer

Here is an old version I have that works on version 1 0 of the  NET framework and does not need generic types   public static Array RemoveAt Array source  int index        if  source    null          throw new ArgumentNullException  source         if  0  gt  index    index  gt   source Length          throw new ArgumentOutOfRangeException  index   index   index is outside the bounds of source array         Array dest   Array CreateInstance source GetType   GetElementType    source Length - 1       Array Copy source  0  dest  0  index       Array Copy source  index   1  dest  index  source Length - index - 1        return dest      This is used like this   class Program       static void Main string   args                string   x   new string 20           for  int i   0  i  lt  x Length  i                x i     i 1  ToString             string   y    string   MyArrayFunctions RemoveAt x  3            for  int i   0  i  lt  y Length  i                Console WriteLine y i

User · Answer

Try below code   myArray   myArray Where s   gt   myArray IndexOf s     indexValue   ToArray      or  myArray   myArray Where s   gt   s     not this    ToArray

User · Answer

Here s how I did it         public static ElementDefinitionImpl   RemoveElementDefAt          ElementDefinition   oldList          int removeIndex                     ElementDefinitionImpl   newElementDefList   new ElementDefinitionImpl  oldList Length - 1             int offset   0          for   int index   0  index  lt  oldList Length  index                           ElementDefinitionImpl elementDef   oldList  index   as ElementDefinitionImpl              if   index    removeIndex                                     This is the one we want to remove  so we won t copy it   But                      every subsequent elementDef will by shifted down by one                  offset   -1                            else                               newElementDefList  index   offset     elementDef                                  return newElementDefList

User · Answer

Here is an old version I have that works on version 1 0 of the  NET framework and does not need generic types   public static Array RemoveAt Array source  int index        if  source    null          throw new ArgumentNullException  source         if  0  gt  index    index  gt   source Length          throw new ArgumentOutOfRangeException  index   index   index is outside the bounds of source array         Array dest   Array CreateInstance source GetType   GetElementType    source Length - 1       Array Copy source  0  dest  0  index       Array Copy source  index   1  dest  index  source Length - index - 1        return dest      This is used like this   class Program       static void Main string   args                string   x   new string 20           for  int i   0  i  lt  x Length  i                x i     i 1  ToString             string   y    string   MyArrayFunctions RemoveAt x  3            for  int i   0  i  lt  y Length  i                Console WriteLine y i

User · Answer

In a normal array you have to shuffle down all the array entries above 2 and then resize it using the Resize method  You might be better off using an ArrayList

User · Answer

In a normal array you have to shuffle down all the array entries above 2 and then resize it using the Resize method  You might be better off using an ArrayList

User · Answer

If you don t want to use List   var foos   new List lt Foo gt  array   foos RemoveAt index   return foos ToArray      You could try this extension method that I haven t actually tested   public static T   RemoveAt lt T gt  this T   source  int index        T   dest   new T source Length - 1       if  index  gt  0           Array Copy source  0  dest  0  index        if  index  lt  source Length - 1           Array Copy source  index   1  dest  index  source Length - index - 1        return dest      And use it like   Foo   bar   GetFoos    bar   bar RemoveAt 2

User · Answer

If you don t want to use List   var foos   new List lt Foo gt  array   foos RemoveAt index   return foos ToArray      You could try this extension method that I haven t actually tested   public static T   RemoveAt lt T gt  this T   source  int index        T   dest   new T source Length - 1       if  index  gt  0           Array Copy source  0  dest  0  index        if  index  lt  source Length - 1           Array Copy source  index   1  dest  index  source Length - index - 1        return dest      And use it like   Foo   bar   GetFoos    bar   bar RemoveAt 2

User · Answer

Here s how I did it         public static ElementDefinitionImpl   RemoveElementDefAt          ElementDefinition   oldList          int removeIndex                     ElementDefinitionImpl   newElementDefList   new ElementDefinitionImpl  oldList Length - 1             int offset   0          for   int index   0  index  lt  oldList Length  index                           ElementDefinitionImpl elementDef   oldList  index   as ElementDefinitionImpl              if   index    removeIndex                                     This is the one we want to remove  so we won t copy it   But                      every subsequent elementDef will by shifted down by one                  offset   -1                            else                               newElementDefList  index   offset     elementDef                                  return newElementDefList

User · Answer

First step You need to convert the array into a list  you could write an extension method like this      Convert An array of string  to a list of string public static List lt string gt  ConnvertArrayToList this string    array            DECLARE a list of string and add all element of the array into it      List lt string gt  myList   new List lt string gt         foreach  string s in array           myList Add s             return myList       Second step Write an extension method to convert back the list into an array     convert a list of string to an array  public static string   ConvertListToArray this List lt string gt  list         string   array   new string list Capacity       array   list Select i   gt  i ToString    ToArray        return array      Last steps Write your final method  but remember to remove the element at index before converting back to an array like the code show  public static string   removeAt string   array  int index         List lt string gt  myList   array ConnvertArrayToList        myList RemoveAt index       return myList ConvertListToArray         examples codes could be find on my blog  keep tracking

[c#] Remove element of a regular array

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