stringOperand + null = ?

[Mark Chambers]

Hi there,

In the expression A + B where A is a string and B isn't, I know that
"B.ToString()" will be called and the results concatenated. If B is null
however does the standard guarantee that "String.Empty" will be used
instead. Thanks.

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Hi there,

In the expression A + B where A is a string and B isn't, I know that
"B.ToString()" will be called and the results concatenated. If B is null
however does the standard guarantee that "String.Empty" will be used
instead. Thanks.

The + operator uses the String.Concat method.

From the specification of the String.Concat method:

"An Empty string is used in place of any null argument."

 

[Mark Chambers]

Hi there,

The + operator uses the String.Concat method.

From the specification of the String.Concat method:

"An Empty string is used in place of any null argument."

Thanks. I didn't know it defers to "String.Concat()".

 

[Jon Skeet [C# MVP]]

Hi there,

In the expression A + B where A is a string and B isn't, I know that
"B.ToString()" will be called and the results concatenated. If B is null
however does the standard guarantee that "String.Empty" will be used
instead. Thanks.

Yup, the spec says:

<quote>
If an operand of string concatenation is null, an empty string is
substituted. Otherwise, any non-string argument is converted to its
string representation by invoking the virtual ToString method inherited
from type object. If ToString returns null, an empty string is
substituted.
</quote>

 

[Mark Chambers]

Yup, the spec says:

<quote>
If an operand of string concatenation is null, an empty string is
substituted. Otherwise, any non-string argument is converted to its
string representation by invoking the virtual ToString method inherited
from type object. If ToString returns null, an empty string is
substituted.
</quote>

Thanks for the confirmation. Appreciated.