I am not sure why you are worried about doubles coming through instead of Decimals but you could just assign with a ternary like this

var B = A1 == null ? null : A1;

This way B will be the same type as A1

Most of the time a Method or Function that takes a Decimal value should also take a Double value, Doubles are smaller than Decimals

Single, Double, Decimal are kind of like Integer types

• Single = 4 bytes (short = 2 bytes)
• Double = 8 Bytes (int = 4 bytes)
• Decimal = 12 bytes (long = 8 bytes)

(Decimal vs. Double)

Note: Assuming that decimal values are necessary

You could just do the conversion after you assign to the variable (after checking for null).

You might be able to assign straight across actually

decimal B = A1 == null ? null : A1;

but you need a nullable decimal (decimal?) Another Assumption

Instead of assigning null to the Decimal you have to assign it's default value using default(decimal?) which I assume comes out as null.

decimal? B = A1 == null ? default(decimal?) : Convert.ToDecimal(A1);

Google and MSDN are awesome resources to figure stuff like this out.

(as well as StackOverflow answers)

playing around with this if you don't want a nullable Decimal you can also write it like this

decimal C = A1 == null ? default(decimal) : Convert.ToDecimal(A1);

I am not sure why you are worried about doubles coming through instead of Decimals but you could just assign with a ternary like this

var B = A1 == null ? null : A1;

This way B will be the same type as A1

Most of the time a Method or Function that takes a Decimal value should also take a Double value, Doubles are smaller than Decimals

Single, Double, Decimal are kind of like Integer types

• Single = 4 bytes (short = 2 bytes)
• Double = 8 Bytes (int = 4 bytes)
• Decimal = 12 bytes (long = 8 bytes)

(Decimal vs. Double)

Note: Assuming that decimal values are necessary

You could just do the conversion after you assign to the variable (after checking for null).

You might be able to assign straight across actually

decimal B = A1 == null ? null : A1;

but you need a nullable decimal (decimal?) Another Assumption

Instead of assigning null to the Decimal you have to assign it's default value using default(decimal?) which I assume comes out as null.

decimal? B = A1 == null ? default(decimal?) : Convert.ToDecimal(A1);

Google and MSDN are awesome resources to figure stuff like this out.

(as well as StackOverflow answers)

playing around with this if you don't want a nullable Decimal you can also write it like this

decimal C = A1 == null ? default(decimal) : Convert.ToDecimal(A1);