What is the integer type in Yaml?

The integer type in YAML represents whole numbers, allowing for various numerical bases and signs, making it a versatile scalar data type for configuration and data serialization.

Understanding YAML Integers

In YAML, an integer is a scalar value that signifies a whole number. Unlike some programming languages, YAML itself doesn't impose strict limits on the size of an integer, often allowing for arbitrary precision, though the actual limits may depend on the specific YAML parser and the programming language it's implemented in. YAML integers can be positive or negative.

Different Bases for Integers

YAML supports expressing integers in several common numerical bases, which enhances flexibility for different use cases, especially when dealing with low-level configurations or bitmasks.

Decimal Integers: These are the most common and represent base-10 numbers. They are written without any special prefixes.
- Examples:
  - count: 123
  - negative_value: -45
  - zero: 0
Octal Integers: Representing base-8 numbers, octal values are identified by a leading zero (0). This convention is important to remember as a number like 010 is not ten, but eight.
- Examples:
  - octal_number: 010 (equivalent to 8 in decimal)
  - permissions: 0644 (a common representation for file permissions)
Hexadecimal Integers: These are base-16 numbers and are distinguished by the prefix 0x. Hexadecimal numbers can include digits 0-9 and letters A-F (case-insensitive) to represent values 10-15.
- Examples:
  - hex_value: 0xA (equivalent to 10 in decimal)
  - rgb_color: 0xFF00FF (representing a magenta color)

Sign and Precision

YAML integers can be prefixed with a + or - sign. While + is usually optional for positive numbers, - is mandatory for negative values.
For example:

positive: +50
negative: -100

The YAML specification, particularly YAML 1.2, suggests that integers should support arbitrary precision. This means, theoretically, an integer can be as large as necessary. However, in practice, parsers written in languages like Java or Python will typically map these to their native integer types (e.g., long in Java, int in Python 3), which do have maximum limits.

Summary of Integer Types

The following table summarizes the different ways to represent integers in YAML:

Type	Prefix	Example	Decimal Equivalent	Description
Decimal	None	`100`	100	Standard base-10 numbers.
Octal	`0` (zero)	`0144`	100	Base-8 numbers, indicated by a leading zero.
Hexadecimal	`0x`	`0x64`	100	Base-16 numbers, indicated by `0x`.

Practical Considerations

When working with YAML integers, especially with leading zeros, be mindful of the interpretation. A number like 08 would be considered invalid octal by most parsers because 8 is not a valid octal digit. Parsers typically treat such cases as errors or fall back to decimal parsing, depending on the implementation. For robust and clear YAML, explicitly using decimal representation is often preferred unless octal or hexadecimal is specifically required for clarity or compatibility with existing systems.

For more details on YAML's data types, refer to the official YAML 1.2 Specification.