Best way to update an element in a generic List

Question

Suppose we have a class called Dog with two strings  Name  and  Id   Now suppose we have a list with 4 dogs in it  If you wanted to change the name of the Dog with the  Id  of  2  what would be the best way to do it   Dog d1   new Dog  Fluffy    1    Dog d2   new Dog  Rex    2    Dog d3   new Dog  Luna    3    Dog d4   new Dog  Willie    4     List lt Dog gt  AllDogs   new List lt Dog gt    AllDogs Add d1   AllDogs Add d2   AllDogs Add d3   AllDogs Add d4

User · Answer

If the list is sorted  as happens to be in the example  a binary search on index certainly works         public static Dog Find List lt Dog gt  AllDogs  string Id                int p   0          int n   AllDogs Count          while  true                        int m    n   p    2              Dog d   AllDogs m               int r   string Compare Id  d Id               if  r    0                  return d              if  m    p                  return null              if  r  lt  0                  n   m              if  r  gt  0                  p   m                    Not sure what the LINQ version of this would be

User · Answer

AllDogs First d   gt  d Id     2   Name    some value     However  a safer version of that might be this   var dog   AllDogs FirstOrDefault d   gt  d Id     2    if  dog    null    dog Name    some value

User · Answer

You could do   var matchingDog   AllDogs FirstOrDefault dog   gt  dog Id     2       This will return the matching dog  else it will return null   You can then set the property like follows   if  matchingDog    null      matchingDog Name    New Dog Name

[c#] Best way to update an element in a generic List

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