how to set null values for float and long datatypes

You can't directly assign null value to any int, float or long datatype variable. To assigning null value you need to declare a special type of variable that is called nullable type. This type of variable is declared with ? symbol.

 

float? num1 = null;

long? num2 = null; 

int? num3 = 250;  

 

Remember you need to assign always the defaul value to nullable type variable as you can't declare it as 

float? num1;

thankf for ur reply

 

i fixed my error by using ? non-nullable type

 

public float ? copay { get;set;}

For primitive types,we have fixed memory size i.e for int we have 4 bytes and char we have 2 bytes. And null is used only for objects because there memory size is not fixed.

 

So by default we have,

 

int a=0;

 

and not

 

int a=null;

 

Same with other primitive types and hence null is only used for objects and not for primitive types.