Passing null arguments to C methods

Question

Is there a way to pass null arguments to C  methods  something like null arguments in c      For example   Is it possible to translate the following c   function to C  method   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

I think the nearest C  equivalent to int  would be ref int   Because ref int  allows the called method to pass a value back to the calling method   int    Can be null  Can be non-null and point to an integer value  If not null  value can be changed  and the change propagates to the caller  Setting to null is not passed back to the caller    ref int    Can be null  Can have an integer value  Value can be always be changed  and the change propagates to the caller  Value can be set to null  and this change will also propagate to the caller

User · Answer

The OP s question is answered well already  but the title is just broad enough that I think it benefits from the following primer   using System  using System Collections Generic  using System Linq  using System Text   namespace consolePlay       class Program               static void Main string   args                        Program test new DateTime                 Program test null                 Program test        lt  lt  lt  Error                    No overload for method  test  takes 0 arguments                   So don t mistake nullable to be optional               Console WriteLine  Done   Return to quit                Console Read                       static public void test DateTime  dteIn                        Console WriteLine       dteIn ToString                               output    1 1 0001 12 00 00 AM     Done   Return to quit

User · Answer

You can use NullableValueTypes  like int   for this  The code would be like this   private void Example int  arg1  int  arg2        if  arg1 HasValue                  do something           if  arg2 HasValue                  do something else

User · Answer

Yes  There are two kinds of types in  NET  reference types and value types   References types  generally classes  are always referred to by references  so they support null without any extra work  This means that if a variable s type is a reference type  the variable is automatically a reference   Value types  e g  int  by default do not have a concept of null  However  there is a wrapper for them called Nullable  This enables you to encapsulate the non-nullable value type and include null information   The usage is slightly different  though      Both of these types mean the same thing  the   is just C  shorthand  private void Example int  arg1  Nullable lt int gt  arg2        if  arg1 HasValue          DoSomething         arg1   null     Valid      arg1   123      Also valid       DoSomethingWithInt arg1      NOT valid      DoSomethingWithInt arg1 Value      Valid

User · Answer

You can use 2 ways  int  or Nullable  both have the same behavior  You could to make a mix without problems but is better choice one to make code cleanest   Option 1  With      private void Example int  arg1  int  arg2                if  arg1 HasValue                          do something                   if  arg1 HasValue                          do something else                   Option 2  With Nullable    private void Example Nullable lt int gt  arg1  Nullable lt int gt  arg2                if  arg1 HasValue                          do something                   if  arg1 HasValue                          do something else                   From C 4 0 comes a new way to do the same with more flexibility  in this case the framework offers optional parameters with default values  of this way you can set a default value if the method is called without all parameters   Option 3  With default values   private void Example int arg1   0  int arg2   1                  do something else

User · Answer

Yes  There are two kinds of types in  NET  reference types and value types   References types  generally classes  are always referred to by references  so they support null without any extra work  This means that if a variable s type is a reference type  the variable is automatically a reference   Value types  e g  int  by default do not have a concept of null  However  there is a wrapper for them called Nullable  This enables you to encapsulate the non-nullable value type and include null information   The usage is slightly different  though      Both of these types mean the same thing  the   is just C  shorthand  private void Example int  arg1  Nullable lt int gt  arg2        if  arg1 HasValue          DoSomething         arg1   null     Valid      arg1   123      Also valid       DoSomethingWithInt arg1      NOT valid      DoSomethingWithInt arg1 Value      Valid

User · Answer

Starting from C  2 0  you can use the nullable generic type Nullable  and in C  there is a shorthand notation the type followed by    e g   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

You can use NullableValueTypes  like int   for this  The code would be like this   private void Example int  arg1  int  arg2        if  arg1 HasValue                  do something           if  arg2 HasValue                  do something else

User · Answer

Yes  There are two kinds of types in  NET  reference types and value types   References types  generally classes  are always referred to by references  so they support null without any extra work  This means that if a variable s type is a reference type  the variable is automatically a reference   Value types  e g  int  by default do not have a concept of null  However  there is a wrapper for them called Nullable  This enables you to encapsulate the non-nullable value type and include null information   The usage is slightly different  though      Both of these types mean the same thing  the   is just C  shorthand  private void Example int  arg1  Nullable lt int gt  arg2        if  arg1 HasValue          DoSomething         arg1   null     Valid      arg1   123      Also valid       DoSomethingWithInt arg1      NOT valid      DoSomethingWithInt arg1 Value      Valid

User · Answer

Yes  There are two kinds of types in  NET  reference types and value types   References types  generally classes  are always referred to by references  so they support null without any extra work  This means that if a variable s type is a reference type  the variable is automatically a reference   Value types  e g  int  by default do not have a concept of null  However  there is a wrapper for them called Nullable  This enables you to encapsulate the non-nullable value type and include null information   The usage is slightly different  though      Both of these types mean the same thing  the   is just C  shorthand  private void Example int  arg1  Nullable lt int gt  arg2        if  arg1 HasValue          DoSomething         arg1   null     Valid      arg1   123      Also valid       DoSomethingWithInt arg1      NOT valid      DoSomethingWithInt arg1 Value      Valid

User · Answer

From C  2 0   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

From C  2 0   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

I think the nearest C  equivalent to int  would be ref int   Because ref int  allows the called method to pass a value back to the calling method   int    Can be null  Can be non-null and point to an integer value  If not null  value can be changed  and the change propagates to the caller  Setting to null is not passed back to the caller    ref int    Can be null  Can have an integer value  Value can be always be changed  and the change propagates to the caller  Value can be set to null  and this change will also propagate to the caller

User · Answer

The OP s question is answered well already  but the title is just broad enough that I think it benefits from the following primer   using System  using System Collections Generic  using System Linq  using System Text   namespace consolePlay       class Program               static void Main string   args                        Program test new DateTime                 Program test null                 Program test        lt  lt  lt  Error                    No overload for method  test  takes 0 arguments                   So don t mistake nullable to be optional               Console WriteLine  Done   Return to quit                Console Read                       static public void test DateTime  dteIn                        Console WriteLine       dteIn ToString                               output    1 1 0001 12 00 00 AM     Done   Return to quit

User · Answer

You can use NullableValueTypes  like int   for this  The code would be like this   private void Example int  arg1  int  arg2        if  arg1 HasValue                  do something           if  arg2 HasValue                  do something else

User · Answer

Starting from C  2 0  you can use the nullable generic type Nullable  and in C  there is a shorthand notation the type followed by    e g   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

I think the nearest C  equivalent to int  would be ref int   Because ref int  allows the called method to pass a value back to the calling method   int    Can be null  Can be non-null and point to an integer value  If not null  value can be changed  and the change propagates to the caller  Setting to null is not passed back to the caller    ref int    Can be null  Can have an integer value  Value can be always be changed  and the change propagates to the caller  Value can be set to null  and this change will also propagate to the caller

User · Answer

Starting from C  2 0  you can use the nullable generic type Nullable  and in C  there is a shorthand notation the type followed by    e g   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

You can use NullableValueTypes  like int   for this  The code would be like this   private void Example int  arg1  int  arg2        if  arg1 HasValue                  do something           if  arg2 HasValue                  do something else

User · Answer

I think the nearest C  equivalent to int  would be ref int   Because ref int  allows the called method to pass a value back to the calling method   int    Can be null  Can be non-null and point to an integer value  If not null  value can be changed  and the change propagates to the caller  Setting to null is not passed back to the caller    ref int    Can be null  Can have an integer value  Value can be always be changed  and the change propagates to the caller  Value can be set to null  and this change will also propagate to the caller

User · Answer

From C  2 0   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

From C  2 0   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

Starting from C  2 0  you can use the nullable generic type Nullable  and in C  there is a shorthand notation the type followed by    e g   private void Example int  arg1  int  arg2        if arg1    null                  do something           if arg2    null                  do something else

User · Answer

You can use 2 ways  int  or Nullable  both have the same behavior  You could to make a mix without problems but is better choice one to make code cleanest   Option 1  With      private void Example int  arg1  int  arg2                if  arg1 HasValue                          do something                   if  arg1 HasValue                          do something else                   Option 2  With Nullable    private void Example Nullable lt int gt  arg1  Nullable lt int gt  arg2                if  arg1 HasValue                          do something                   if  arg1 HasValue                          do something else                   From C 4 0 comes a new way to do the same with more flexibility  in this case the framework offers optional parameters with default values  of this way you can set a default value if the method is called without all parameters   Option 3  With default values   private void Example int arg1   0  int arg2   1                  do something else

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