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Integers

There are four signed integer types, and four unsigned integer types:

Type Length Minimum Value Maximum Value
Int8 8 -128 127
Int16 16 −32,768 32,767
Int32 32 −2,147,483,648 2,147,483,647
Int64 64 −263 263 - 1
UInt8 8 0 255
UInt16 16 0 65,535
UInt32 32 0 4,294,967,295
UInt64 64 0 264 - 1

An integer literal is an optional + or - sign, followed by a sequence of digits and underscores, optionally followed by a suffix. If no suffix is present, the literal's type is the lowest between Int32, Int64 and UInt64 in which the number fits:

1      # Int32

1_i8   # Int8
1_i16  # Int16
1_i32  # Int32
1_i64  # Int64

1_u8   # UInt8
1_u16  # UInt16
1_u32  # UInt32
1_u64  # UInt64

+10    # Int32
-20    # Int32

2147483648          # Int64
9223372036854775808 # UInt64

The underscore _ before the suffix is optional.

Underscores can be used to make some numbers more readable:

1_000_000 # better than 1000000

Binary numbers start with 0b:

0b1101 # == 13

Octal numbers start with a 0o:

0o123 # == 83

Hexadecimal numbers start with 0x:

0xFE012D # == 16646445
0xfe012d # == 16646445

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https://crystal-lang.org/docs/syntax_and_semantics/literals/integers.html