CODEWITHSUNDEEP
.nettypestype-inference
Matthew Layton
Matthew Layton

Reputation: 42260

Why does .NET naturally assume certain types?

Consider the following code:

var x = 32;

The number 32 will fit in within sbyte, byte, short, ushort, etc.

Why does .NET assume this is an int?

Same question for var x = 3.2; .NET assumes double

Upvotes: 1

Views: 53

Answers (1)

xanatos
xanatos

Reputation: 111860

Why does .NET assume this is an int?

Wrong question/subject. It is the C# compiler that assume this is an int.

Taken from 2.4.4.2 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.

and from 2.4.4.3 Real literals:

If no real type suffix is specified, the type of the real literal is double.

Another important "trick" of the compiler, that makes this legal:

byte b = 5;

(normally 5 would be an int, and there is no implicit conversion from int to byte), but:

Taken from 6.1.6 Implicit constant expression conversions:

An implicit constant expression conversion permits the following conversions:

  • A constant-expression (Section 7.15) of type int can be converted to type sbyte, byte, short, ushort, uint, or ulong, provided the value of the constant-expression is within the range of the destination type.

  • A constant-expression of type long can be converted to type ulong, provided the value of the constant-expression is not negative.

Upvotes: 4

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