Adding values to a C array

Question

Probably a really simple one this - I m starting out with C  and need to add values to an array  for example   int   terms   for int runs   0  runs  lt  400  runs          terms     runs      For those who have used PHP  here s what I m trying to do in C     arr   array    for   i   0   i  lt  10   i           arr      i

User · Accepted Answer

You can do this way -  int   terms   new int 400   for  int runs   0  runs  lt  400  runs          terms runs    value      Alternatively  you can use Lists - the advantage with lists being  you don t need to know the array size when instantiating the list   List lt int gt  termsList   new List lt int gt     for  int runs   0  runs  lt  400  runs          termsList Add value         You can convert it back to an array if you would like to int   terms   termsList ToArray      Edit  a  for loops on List lt T  are a bit more than 2 times cheaper than foreach loops on List lt T   b  Looping on array is around 2 times cheaper than looping on List lt T   c  looping on array using for is 5 times cheaper than looping on List lt T  using foreach  which most of us do

User · Answer

I think this is the best method how to do that Array Push Example public void ArrayPush lt T gt  ref T   table  object value        Array Resize ref table  table Length   1      Resizing the array for the cloned length   -    1      table SetValue value  table Length - 1      Setting the value for the new element

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Just a different approach   int runs   0   bool batting   true   string scorecard   while  batting   runs  lt  400      scorecard          runs     return scorecard Split

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static void Main string   args                        int   arrayname   new int 5    arrayname is an array of 5 integer  5  mean in array  0   1   2   3   4   5  because array starts with zero               int i  j                initialize elements of array arrayname               for  i   0  i  lt  5  i                                  arrayname i    i   100                                output each array element value               for  j   0  j  lt  5  j                                  Console WriteLine  Element and output value   0    1   j arrayname j                              Console ReadKey     Obtains the next character or function key pressed by the user                                  The pressed key is displayed in the console window

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If you re writing in C  3  you can do it with a one-liner   int   terms   Enumerable Range 0  400  ToArray      This code snippet assumes that you have a using directive for System Linq at the top of your file   On the other hand  if you re looking for something that can be dynamically resized  as it appears is the case for PHP  I ve never actually learned it   then you may want to use a List instead of an int    Here s what that code would look like   List lt int gt  terms   Enumerable Range 0  400  ToList      Note  however  that you cannot simply add a 401st element by setting terms 400  to a value  You d instead need to call Add    like this   terms Add 1337

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I will add this for a another variant  I prefer this type of functional coding lines more   Enumerable Range 0  400  Select x   gt  x  ToArray

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Using Linq s method Concat makes this simple  int   array   new int     3  4     array   array Concat new int     2    ToArray      result 3 4 2

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Just a different approach   int runs   0   bool batting   true   string scorecard   while  batting   runs  lt  400      scorecard          runs     return scorecard Split

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You have to allocate the array first   int    terms   new int 400      allocate an array of 400 ints for int runs   0  runs  lt  terms Length  runs       Use Length property rather than the 400 magic number again       terms runs    value

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You can t just add an element to an array easily  You can set the element at a given position as fallen888 outlined  but I recommend to use a List lt int gt  or a Collection lt int gt  instead  and use ToArray   if you need it converted into an array

User · Answer

Answers on how to do it using an array are provided here   However  C  has a very handy thing called System Collections     Collections are fancy alternatives to using an array  though many of them use an array internally   For example  C  has a collection called List that functions very similar to the PHP array   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i

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static void Main string   args                        int   arrayname   new int 5    arrayname is an array of 5 integer  5  mean in array  0   1   2   3   4   5  because array starts with zero               int i  j                initialize elements of array arrayname               for  i   0  i  lt  5  i                                  arrayname i    i   100                                output each array element value               for  j   0  j  lt  5  j                                  Console WriteLine  Element and output value   0    1   j arrayname j                              Console ReadKey     Obtains the next character or function key pressed by the user                                  The pressed key is displayed in the console window

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int ArraySize   400   int   terms   new int ArraySize     for int runs   0  runs  lt  ArraySize  runs           terms runs    runs       That would be how I d code it

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You can do this is with a list  here is how List lt string gt  info   new List lt string gt     info Add  quot finally worked quot     and if you need to return this array do return info ToArray

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You have to allocate the array first   int    terms   new int 400      allocate an array of 400 ints for int runs   0  runs  lt  terms Length  runs       Use Length property rather than the 400 magic number again       terms runs    value

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To add the list values to string array using C   without using ToArray   method          List lt string gt  list   new List lt string gt             list Add  one            list Add  two            list Add  three            list Add  four            list Add  five            string   values   new string list Count    assigning the count for array         for int i 0 i lt list Count i                          values i    list i  ToString                Output of the value array contains   one  two  three  four  five

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You can do this is with a list  here is how List lt string gt  info   new List lt string gt     info Add  quot finally worked quot     and if you need to return this array do return info ToArray

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int   terms   new int 400    for int runs   0  runs  lt  400  runs          terms runs    value

User · Answer

You have to allocate the array first   int    terms   new int 400      allocate an array of 400 ints for int runs   0  runs  lt  terms Length  runs       Use Length property rather than the 400 magic number again       terms runs    value

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one approach is to fill an array via LINQ  if you want to fill an array with one element  you can simply write  string   arrayToBeFilled  arrayToBeFilled  arrayToBeFilled Append  str   ToArray      furthermore  If you want to fill an array with multiple elements you can use the  previous code in a loop    the array you want to fill values in string   arrayToBeFilled    list of values that you want to fill inside an array List lt string gt  listToFill   new List lt string gt     a1    a2    a3       looping through list to start filling the array  foreach  string str in listToFill      here are the LINQ extensions arrayToBeFilled  arrayToBeFilled Append str  ToArray

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This seems like a lot less trouble to me  var usageList   usageArray ToList    usageList Add  quot newstuff quot    usageArray   usageList ToArray

User · Answer

If you re writing in C  3  you can do it with a one-liner   int   terms   Enumerable Range 0  400  ToArray      This code snippet assumes that you have a using directive for System Linq at the top of your file   On the other hand  if you re looking for something that can be dynamically resized  as it appears is the case for PHP  I ve never actually learned it   then you may want to use a List instead of an int    Here s what that code would look like   List lt int gt  terms   Enumerable Range 0  400  ToList      Note  however  that you cannot simply add a 401st element by setting terms 400  to a value  You d instead need to call Add    like this   terms Add 1337

User · Answer

You can t do this directly  However  you can use Linq to do this  List lt int gt  termsLst new List lt int gt     for  int runs   0  runs  lt  400  runs          termsLst Add runs     int   terms   termsLst ToArray     If the array terms wasn t empty in the beginning  you can convert it to List first then do your stuf  Like      List lt int gt  termsLst   terms ToList        for  int runs   0  runs  lt  400  runs                  termsLst Add runs             terms   termsLst ToArray      Note  don t miss adding  using System Linq   at the begaining of the file

User · Answer

Answers on how to do it using an array are provided here   However  C  has a very handy thing called System Collections     Collections are fancy alternatives to using an array  though many of them use an array internally   For example  C  has a collection called List that functions very similar to the PHP array   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i

User · Answer

By 2019 you can use Append  Prepend using LinQ in just one line using System Linq   and then  terms  terms Append 21  ToArray

User · Answer

int ArraySize   400   int   terms   new int ArraySize     for int runs   0  runs  lt  ArraySize  runs           terms runs    runs       That would be how I d code it

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one approach is to fill an array via LINQ  if you want to fill an array with one element  you can simply write  string   arrayToBeFilled  arrayToBeFilled  arrayToBeFilled Append  str   ToArray      furthermore  If you want to fill an array with multiple elements you can use the  previous code in a loop    the array you want to fill values in string   arrayToBeFilled    list of values that you want to fill inside an array List lt string gt  listToFill   new List lt string gt     a1    a2    a3       looping through list to start filling the array  foreach  string str in listToFill      here are the LINQ extensions arrayToBeFilled  arrayToBeFilled Append str  ToArray

User · Answer

I will add this for a another variant  I prefer this type of functional coding lines more   Enumerable Range 0  400  Select x   gt  x  ToArray

User · Answer

Using Linq s method Concat makes this simple  int   array   new int     3  4     array   array Concat new int     2    ToArray      result 3 4 2

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int ArraySize   400   int   terms   new int ArraySize     for int runs   0  runs  lt  ArraySize  runs           terms runs    runs       That would be how I d code it

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If you don t know the size of the Array or already have an existing array that you are adding to  You can go about this in two ways  The first is using a generic List lt T gt   To do this you will want convert the array to a var termsList   terms ToList    and use the Add method  Then when done use the var terms   termsList ToArray    method to convert back to an array  var terms   default int     var termsList   terms    null   new List lt int gt      terms ToList     for var i   0  i  lt  400  i        termsList Add i    terms   termsList ToArray     The second way is resizing the current array  var terms   default int      for var i   0  i  lt  400  i          if terms    null          terms   new int 1       else             Array Resize lt int gt  ref terms  terms Length   1            terms terms Length - 1    i     If you are using  NET 3 5 Array Add       Both of these will allow you to do it dynamically  If you will be adding lots of items then just use a List lt T gt   If it s just a couple of items then it will have better performance resizing the array  This is because you take more of a hit for creating the List lt T gt  object  Times in ticks  3 items  Array Resize Time  6 List Add Time  16  400 items  Array Resize Time  305 List Add Time  20

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arrayname is an array of 5 integer               int   arrayname   new int 5               int i  j                initialize elements of array arrayname               for  i   0  i  lt  5  i                                  arrayname i    i   100

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I think this is the best method how to do that Array Push Example public void ArrayPush lt T gt  ref T   table  object value        Array Resize ref table  table Length   1      Resizing the array for the cloned length   -    1      table SetValue value  table Length - 1      Setting the value for the new element

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Based on the answer of Thracx  I don t have enough points to answer    public static T   Add lt T gt  this T   target  params T   items                   Validate the parameters         if  target    null                target   new T                          if  items   null                items   new T                              Join the arrays         T   result   new T target Length   items Length           target CopyTo result  0           items CopyTo result  target Length           return result          This allows to add more than just one item to the array  or just pass an array as a parameter to join two arrays

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If you re writing in C  3  you can do it with a one-liner   int   terms   Enumerable Range 0  400  ToArray      This code snippet assumes that you have a using directive for System Linq at the top of your file   On the other hand  if you re looking for something that can be dynamically resized  as it appears is the case for PHP  I ve never actually learned it   then you may want to use a List instead of an int    Here s what that code would look like   List lt int gt  terms   Enumerable Range 0  400  ToList      Note  however  that you cannot simply add a 401st element by setting terms 400  to a value  You d instead need to call Add    like this   terms Add 1337

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C  arrays are fixed length and always indexed  Go with Motti s solution   int    terms   new int 400   for int runs   0  runs  lt  400  runs          terms runs    value      Note that this array is a dense array  a contiguous block of 400 bytes where you can drop things  If you want a dynamically sized array  use a List lt int    List lt int gt  terms   new List lt int gt     for int runs   0  runs  lt  400  runs           terms Add runs       Neither int   nor List lt int  is an associative array -- that would be a Dictionary lt   in C     Both arrays and lists are dense

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C  arrays are fixed length and always indexed  Go with Motti s solution   int    terms   new int 400   for int runs   0  runs  lt  400  runs          terms runs    value      Note that this array is a dense array  a contiguous block of 400 bytes where you can drop things  If you want a dynamically sized array  use a List lt int    List lt int gt  terms   new List lt int gt     for int runs   0  runs  lt  400  runs           terms Add runs       Neither int   nor List lt int  is an associative array -- that would be a Dictionary lt   in C     Both arrays and lists are dense

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You can t do this directly  However  you can use Linq to do this  List lt int gt  termsLst new List lt int gt     for  int runs   0  runs  lt  400  runs          termsLst Add runs     int   terms   termsLst ToArray     If the array terms wasn t empty in the beginning  you can convert it to List first then do your stuf  Like      List lt int gt  termsLst   terms ToList        for  int runs   0  runs  lt  400  runs                  termsLst Add runs             terms   termsLst ToArray      Note  don t miss adding  using System Linq   at the begaining of the file

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int ArraySize   400   int   terms   new int ArraySize     for int runs   0  runs  lt  ArraySize  runs           terms runs    runs       That would be how I d code it

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Based on the answer of Thracx  I don t have enough points to answer    public static T   Add lt T gt  this T   target  params T   items                   Validate the parameters         if  target    null                target   new T                          if  items   null                items   new T                              Join the arrays         T   result   new T target Length   items Length           target CopyTo result  0           items CopyTo result  target Length           return result          This allows to add more than just one item to the array  or just pass an array as a parameter to join two arrays

User · Answer

To add the list values to string array using C   without using ToArray   method          List lt string gt  list   new List lt string gt             list Add  one            list Add  two            list Add  three            list Add  four            list Add  five            string   values   new string list Count    assigning the count for array         for int i 0 i lt list Count i                          values i    list i  ToString                Output of the value array contains   one  two  three  four  five

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By 2019 you can use Append  Prepend using LinQ in just one line using System Linq   and then  terms  terms Append 21  ToArray

User · Answer

int   terms   new int 400    for int runs   0  runs  lt  400  runs          terms runs    value

User · Answer

You can t just add an element to an array easily  You can set the element at a given position as fallen888 outlined  but I recommend to use a List lt int gt  or a Collection lt int gt  instead  and use ToArray   if you need it converted into an array

User · Answer

If you don t know the size of the Array or already have an existing array that you are adding to  You can go about this in two ways  The first is using a generic List lt T gt   To do this you will want convert the array to a var termsList   terms ToList    and use the Add method  Then when done use the var terms   termsList ToArray    method to convert back to an array  var terms   default int     var termsList   terms    null   new List lt int gt      terms ToList     for var i   0  i  lt  400  i        termsList Add i    terms   termsList ToArray     The second way is resizing the current array  var terms   default int      for var i   0  i  lt  400  i          if terms    null          terms   new int 1       else             Array Resize lt int gt  ref terms  terms Length   1            terms terms Length - 1    i     If you are using  NET 3 5 Array Add       Both of these will allow you to do it dynamically  If you will be adding lots of items then just use a List lt T gt   If it s just a couple of items then it will have better performance resizing the array  This is because you take more of a hit for creating the List lt T gt  object  Times in ticks  3 items  Array Resize Time  6 List Add Time  16  400 items  Array Resize Time  305 List Add Time  20

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int   terms   new int 400    for int runs   0  runs  lt  400  runs          terms runs    value

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Using a List as an intermediary is the easiest way  as others have described  but since your input is an array and you don t just want to keep the data in a List  I presume you might be concerned about performance   The most efficient method is likely allocating a new array and then using Array Copy or Array CopyTo   This is not hard if you just want to add an item to the end of the list   public static T   Add lt T gt  this T   target  T item        if  target    null                  TODO  Return null or throw ArgumentNullException            T   result   new T target Length   1       target CopyTo result  0       result target Length    item      return result      I can also post code for an Insert extension method that takes a destination index as input  if desired   It s a little more complicated and uses the static method Array Copy 1-2 times

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int   terms   new int 400    for int runs   0  runs  lt  400  runs          terms runs    value

User · Answer

You can t just add an element to an array easily  You can set the element at a given position as fallen888 outlined  but I recommend to use a List lt int gt  or a Collection lt int gt  instead  and use ToArray   if you need it converted into an array

User · Answer

arrayname is an array of 5 integer               int   arrayname   new int 5               int i  j                initialize elements of array arrayname               for  i   0  i  lt  5  i                                  arrayname i    i   100

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C  arrays are fixed length and always indexed  Go with Motti s solution   int    terms   new int 400   for int runs   0  runs  lt  400  runs          terms runs    value      Note that this array is a dense array  a contiguous block of 400 bytes where you can drop things  If you want a dynamically sized array  use a List lt int    List lt int gt  terms   new List lt int gt     for int runs   0  runs  lt  400  runs           terms Add runs       Neither int   nor List lt int  is an associative array -- that would be a Dictionary lt   in C     Both arrays and lists are dense

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int   terms   new int 10     create 10 empty index in array terms    fill value   400 for every index  run  in the array   terms Length is the total length of the array  it is equal to 10 in this case  for  int run   0  run  lt  terms Length  run           terms run    400       print value from each of the index for  int run   0  run  lt  terms Length  run          Console WriteLine  Value in index  0   t 1   run  terms run       Console ReadLine           Output       Value in index 0     400   Value in index 1     400   Value in index 2     400   Value in index 3     400   Value in index 4     400   Value in index 5     400   Value in index 6     400   Value in index 7     400   Value in index 8     400   Value in index 9     400

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Answers on how to do it using an array are provided here   However  C  has a very handy thing called System Collections     Collections are fancy alternatives to using an array  though many of them use an array internally   For example  C  has a collection called List that functions very similar to the PHP array   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i

User · Answer

You can t just add an element to an array easily  You can set the element at a given position as fallen888 outlined  but I recommend to use a List lt int gt  or a Collection lt int gt  instead  and use ToArray   if you need it converted into an array

User · Answer

int   terms   new int 10     create 10 empty index in array terms    fill value   400 for every index  run  in the array   terms Length is the total length of the array  it is equal to 10 in this case  for  int run   0  run  lt  terms Length  run           terms run    400       print value from each of the index for  int run   0  run  lt  terms Length  run          Console WriteLine  Value in index  0   t 1   run  terms run       Console ReadLine           Output       Value in index 0     400   Value in index 1     400   Value in index 2     400   Value in index 3     400   Value in index 4     400   Value in index 5     400   Value in index 6     400   Value in index 7     400   Value in index 8     400   Value in index 9     400

User · Answer

This seems like a lot less trouble to me  var usageList   usageArray ToList    usageList Add  quot newstuff quot    usageArray   usageList ToArray

User · Answer

If you re writing in C  3  you can do it with a one-liner   int   terms   Enumerable Range 0  400  ToArray      This code snippet assumes that you have a using directive for System Linq at the top of your file   On the other hand  if you re looking for something that can be dynamically resized  as it appears is the case for PHP  I ve never actually learned it   then you may want to use a List instead of an int    Here s what that code would look like   List lt int gt  terms   Enumerable Range 0  400  ToList      Note  however  that you cannot simply add a 401st element by setting terms 400  to a value  You d instead need to call Add    like this   terms Add 1337

User · Answer

If you really need an array the following is probly the simplest   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i      int    terms   list ToArray

User · Answer

If you really need an array the following is probly the simplest   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i      int    terms   list ToArray

User · Answer

C  arrays are fixed length and always indexed  Go with Motti s solution   int    terms   new int 400   for int runs   0  runs  lt  400  runs          terms runs    value      Note that this array is a dense array  a contiguous block of 400 bytes where you can drop things  If you want a dynamically sized array  use a List lt int    List lt int gt  terms   new List lt int gt     for int runs   0  runs  lt  400  runs           terms Add runs       Neither int   nor List lt int  is an associative array -- that would be a Dictionary lt   in C     Both arrays and lists are dense

User · Answer

You have to allocate the array first   int    terms   new int 400      allocate an array of 400 ints for int runs   0  runs  lt  terms Length  runs       Use Length property rather than the 400 magic number again       terms runs    value

User · Answer

Answers on how to do it using an array are provided here   However  C  has a very handy thing called System Collections     Collections are fancy alternatives to using an array  though many of them use an array internally   For example  C  has a collection called List that functions very similar to the PHP array   using System Collections Generic      Create a List  and it can only contain integers  List lt int gt  list   new List lt int gt      for  int i   0  i  lt  400  i         list Add i

User · Answer

Using a List as an intermediary is the easiest way  as others have described  but since your input is an array and you don t just want to keep the data in a List  I presume you might be concerned about performance   The most efficient method is likely allocating a new array and then using Array Copy or Array CopyTo   This is not hard if you just want to add an item to the end of the list   public static T   Add lt T gt  this T   target  T item        if  target    null                  TODO  Return null or throw ArgumentNullException            T   result   new T target Length   1       target CopyTo result  0       result target Length    item      return result      I can also post code for an Insert extension method that takes a destination index as input  if desired   It s a little more complicated and uses the static method Array Copy 1-2 times

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