How to convert List string to List int

Question

My question is part of this problem     I recieve a collection of id s from a form  I need to get the keys  convert them to integers and select the matching records from the DB      HttpPost  public ActionResult Report FormCollection collection        var listofIDs   collection AllKeys ToList             List lt string gt  to List lt int gt      List lt Dinner gt  dinners   new List lt Dinner gt         dinners  repository GetDinners listofIDs       return View dinners

User · Accepted Answer

listofIDs Select int Parse  ToList

User · Answer

What no TryParse  Safe LINQ version that filters out invalid ints  for C  6 0 and below    List lt int gt   ints   strings      Select s   gt    int i  return int TryParse s  out i    i    int  null          Where i   gt  i HasValue       Select i   gt  i Value       ToList      credit to Olivier Jacot-Descombes for the idea and the C  7 0 version

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Using Linq      List lt string gt  listofIDs   collection AllKeys ToList      List lt int gt  myStringList   listofIDs Select s   gt  int Parse s   ToList

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yourEnumList Select s   gt   int s  ToList

User · Answer

I know it s old post  but I thought this is a good addition  You can use List lt T gt  ConvertAll lt TOutput gt   List lt int gt  integers   strings ConvertAll s   gt  Int32 Parse s

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Convert string value into integer list   var myString    010    int myInt  List lt int gt  B   myString ToCharArray   Where x   gt  int TryParse x ToString    out myInt   Select x   gt  int Parse x ToString     ToList

User · Answer

Here is a safe variant that filters out invalid ints  List lt int gt  ints   strings      Select s   gt  Int32 TryParse s  out int n    n    int  null       Where n   gt  n HasValue       Select n   gt  n Value       ToList     It uses an out variable introduced with C 7 0  This other variant returns a list of nullable ints where null entries are inserted for invalid ints  i e  it preserves the original list count   List lt int  gt  nullableInts   strings      Select s   gt  Int32 TryParse s  out int n    n    int  null       ToList

User · Answer

intList   Array ConvertAll stringList  int Parse  ToList

User · Answer

Another way to accomplish this would be using a linq statement  The recomended answer did not work for me in  NetCore2 0  I was able to figure it out however and below would also work if you are using newer technology     HttpPost  public ActionResult Report FormCollection collection        var listofIDs   collection ToList   Select x   gt  x ToString         List lt Dinner gt  dinners   new List lt Dinner gt         dinners   repository GetDinners listofIDs       return View dinners

User · Answer

Using Linq   var intList   stringList Select s   gt  Convert ToInt32 s   ToList

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public List lt int gt  ConvertStringListToIntList List lt string gt  list            List lt int gt  resultList   new List lt int gt          for  int i   0  i  lt  list Count  i            resultList Add Convert ToInt32 list i           return resultList

User · Answer

This may be overkill for this simple problem  But for Try-Do methods in connection with Linq  I tend to use anonymous classes for more expressive code  It is similar to the answers from Olivier Jacot-Descombes and BA TabNabber   List lt int gt  ints   strings      Select idString   gt  new   ParseSuccessful   Int32 TryParse idString  out var id   Value   id         Where id   gt  id ParseSuccessful       Select id   gt  id Value       ToList

User · Answer

You can use it via LINQ       var selectedEditionIds   input SelectedEditionIds Split      ToArray                                Where i   gt   string IsNullOrWhiteSpace i                                 amp  amp  int TryParse i out int validNumber                                Select x  gt int Parse x   ToList

User · Answer

This is the simplest way  I think    var listOfStrings    new       4    5    6     ToList    var listOfInts   listOfStrings Select lt string  int gt  q   gt  Convert ToInt32 q

[c#] How to convert List<string> to List<int>?

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