how to set a value of char array to null?

Question

for example when I wrote:

Char[] test = new Char[3] {a,b,c};
test[2] = null;

it says Cannot convert null to 'char' because it is a non-nullable value type

if I need to empty that array of char, is there a solution?

Solution 1

Use a nullable char:

char?[] test = new char?[3] {a,b,c};
test[2] = null;

The drawback is you have to check for a value each time you access the array:

char c = test[1];  // illegal

if(test[1].HasValue)
{
    char c = test[1].Value;
}

or you could use a "magic" char value to represent null, like \0:

char[] test = new char[3] {a,b,c};
test[2] = '\0';

Solution 2

You can't do it because, as the error says, char is a value type.

You could do this:

char?[] test = new char?[3]{a,b,c};
test[2] = null;

because you are now using the nullable char.

If you don't want to use a nullable type, you will have to decide on some value to represent an empty cell in your array.

Solution 3

As the error states, char is non-nullable. Try using default instead:

test[2] = default(char);

Note that this is essentially a null byte '\0'. This does not give you a null value for the index. If you truly need to consider a null scenario, the other answers here would work best (using a nullable type).

Solution 4

You could do:

test[2] = Char.MinValue;

If you had tests to see if a value was "null" somewhere in your code, you'd do it like this:

if (test[someArrayIndex] == Char.MinValue)
{
   // Do stuff.
}

Also, Char.MinValue == default(char)

Solution 5

you can set test to null

test = null;

but not test[2] because it is char - hence value type

View more solutions

Comments

[Jeppe Stig Nielsen]

default(char) gives the null character. Why not make that explicit and say test[2] = '\0';? I would recommend that (if you want to use this character as a kind of "magic value").

[jheddings]

Just a quick suggestion might be to use default(char) for the "magic" value. IMHO, it provides a similar mental model for considering the value "uninitialized" or "unspecified."

[jheddings]

Only for consistency... I use default in many cases where the type is not know up front (i.e. generics or reflection). It helps me keep a consistent mental model that default => "unspecified" or "uninitialized."

[D Stanley]

Fair enough - using \0 as null is a holdover from my C++ days :)

[jheddings]

Nothing wrong with that... They are the same in this case, after all.

[Hendra Anggrian]

that '\0' works perfectly. I'm sorry I have to ignore the first 2 packs of codes above because I'm searching for the simplest one. Thanks mate!