Why c# treats 0 as int and not as short/decimal etc?

Question

In c# when i say :

var s = 0;

what should be type of s ? it makes it int32. then seems like var is not usable for types like short and others(?).

Answer 1

From the specification (§ 2.4.4.2):

If the literal has no suffix, it has the first of these types in which its value can be represented: int, uint, long, ulong.

So smaller types are not automatically inferred. You can add a cast to force such a smaller type:

var s = (short)0;

Answer 2

Look at this post here at StackOverflow.

You can specify a postfix for all numbers.

var i = 0;
var d = 0d;
var f = 0f;
var l = 0L;
var m = 0m;

Answer 3

As per the C# language standard, specifically §2.4.4.2 on integer literals:

The type of an integer literal is determined as follows:

• If the literal has no suffix, it has the first of these types in which its value can be represented: int, uint, long, ulong.
• If the literal is suffixed by U or u, it has the first of these types in which its value can be represented: uint, ulong.
• If the literal is suffixed by L or l, it has the first of these types in which its value can be represented: long, ulong.
• If the literal is suffixed by UL, Ul, uL, ul, LU, Lu, lU, or lu, it is of type ulong.

The first rule is all that needs to be applied here. The literal 0 has no suffix and can be represented as type int (or, in BCL terms, Int32), so that's the type it has.

As you can infer from the above, to change the type of a literal, you can append a suffix to it. For example, the literal 0u will be of type uint. Alternatively, you could explicitly cast the literal to a different type; for example: (short)0 would cause the compiler to treat the literal as a short.