| explicitIntegerConstant | integer literal |
| Syntax | An explicitIntegerConstant is a sequence of one or more decimal digits (0 to 9) optionally preceded by a plus or minus sign. This is an alternate form that specifies a number base (such as base 2 or base 16).
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| Example | In the following, the explicit integer constants are 0, 115 and 5.
var count : int := 0
const height := 115
…
count := height - 5
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| Details | In current implementations of Turing, the range of the int (integer) type is from -2147483647 to 2147483647. In other words, the maximum size of integer is 2**31 - 1. This is the range that fits into four bytes, with one pattern left over (the largest negative 4-byte number) to represent the uninitialized value. See maxint. Values can be written in base 2 or 16 or any other base in the range 2 to 36 (36 because there are 10 digits and 26 letters). This form begins with the base, such as 16, then #, and then the value written in that base, for example, 16#A has the value 10. The letters a, b, c … represent the digit values 10, 11, 12 … Capital letters A, B, C … can be used instead of lower case. Here are some examples.
Here is an example of using these:
const maxnat1 := 16#FF % Largest 1-byte natural number
const maxint2 := 16#7FFF % Largest 2-byte integer
You should be careful to avoid confusion about patterns such as 16#FFFF. It is tempting to think that this is the value 1, because the bit pattern (2-byte two's complement internal representation) for 1 is the same as the bit pattern for 16#FFFF = 32767. However, the value (as opposed to the internal representation) of 1 and 32767 are different.
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| See also | int, maxint (the largest integer value), nat (positive values only) and intn (n-byte integers). See also intstr and natstr which convert integer and natural number values to corresponding character strings in any base, for example intstr (4, 0, 2) = "100".
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