Untyped numeric constants with no limits
Constants may be typed or untyped.
const a uint = 17 const b = 55
An untyped constant has no limits. When it’s used in a context that requires a type, a type will be inferred and a limit applied.
const big = 10000000000 // Ok, even thought it's too big for an int. const bigger = big * 100 // Still ok. var i int = big / 100 // No problem: the new result fits in an int. // Compile time error: "constant 10000000000 overflows int" var j int = big
The inferred type is determined by the syntax of the value:
The other possibilities are
rune (alias for
Go does not have enumerated types. Instead, you can use the special name
iota in a single
const declaration to get a series of increasing values. When an initialization expression is omitted for a
const, it reuses the preceding expression.
const ( red = iota // red == 0 blue // blue == 1 green // green == 2 )
See Enumeration with string representation for a detailed example.