Julia provides a comprehensive set of integer types, allowing for precise control over memory usage and value ranges. These types are primarily distinguished by their bit size, determining the maximum and minimum values they can hold, and whether they are signed (can represent negative numbers) or unsigned (only non-negative numbers).
Standard Integer Types
Julia includes signed and unsigned integer types for 8, 16, 32, 64, and 128 bits. Each type explicitly states its bit size, ensuring predictable behavior across different systems.
Here's a breakdown of the standard integer types in Julia, their bit sizes, and their corresponding value ranges:
| Type | Bits | Signed? | Minimum Value | Maximum Value |
|---|---|---|---|---|
Int8 |
8 | ✓ | -128 (-2^7) | 127 (2^7 - 1) |
UInt8 |
8 | 0 | 255 (2^8 - 1) | |
Int16 |
16 | ✓ | -32,768 (-2^15) | 32,767 (2^15 - 1) |
UInt16 |
16 | 0 | 65,535 (2^16 - 1) | |
Int32 |
32 | ✓ | -2,147,483,648 (-2^31) | 2,147,483,647 (2^31 - 1) |
UInt32 |
32 | 0 | 4,294,967,295 (2^32 - 1) | |
Int64 |
64 | ✓ | -9,223,372,036,854,775,808 (-2^63) | 9,223,372,036,854,775,807 (2^63 - 1) |
UInt64 |
64 | 0 | 18,446,744,073,709,551,615 (2^64 - 1) | |
Int128 |
128 | ✓ | -2^127 | 2^127 - 1 |
UInt128 |
128 | 0 | 2^128 - 1 |
Note: The values highlighted in bold are specifically mentioned in the reference as examples of integer types and their largest values.
Default Integer Types (Int and UInt)
Julia also defines default integer types, Int and UInt, which are aliases for the native integer size of your system. This makes code more portable while leveraging optimal performance.
- On 64-bit systems (the most common today),
Intis an alias forInt64, andUIntis an alias forUInt64. - On 32-bit systems,
Intwould beInt32, andUIntwould beUInt32.
You can check the default integer size on your system by running typemin(Int) or typemax(Int) in the Julia REPL.
Practical Insights and Examples
Understanding integer sizes is crucial for avoiding overflow errors, which occur when a calculation results in a number larger or smaller than the type can hold.
-
Checking Type and Range:
# Check the type of an integer literal typeof(1) # Output: Int64 (on a 64-bit system) # Check the default unsigned integer type typeof(0x1) # Output: UInt64 (on a 64-bit system) # Get the minimum and maximum values for a specific type typemin(Int32) # Output: -2147483648 typemax(UInt16) # Output: 65535 # Check the bit size of a type sizeof(Int16) # Output: 2 bytes (16 bits) -
Explicit Type Declaration:
You can explicitly specify the type of an integer literal by preceding the number with the type name, or by appending a hexadecimal literal withUfor unsigned types.x = Int8(100) # x is an Int8 y = UInt16(50000) # y is a UInt16 z = 0xFF # z is a UInt8 by default for hex literals fitting in 8 bits w = 0xFFFFu # w is an unsigned integer, typically UInt16 or larger
For more in-depth information, refer to the official Julia documentation on integers and floating-point numbers: Integers and Floating-Point Numbers
