Rune
A rune is Go’s predeclared alias for int32 that represents a Unicode code point.
100 Go Mistakes and How to Avoid Them
A rune is Go's representation of a Unicode code point, implemented as an alias of int32.
- How it is used
- Prevents byte-versus-code-point mistakes when counting, indexing, or iterating over Go strings.
- How deep it goes
- Defines rune and traces incorrect iteration through its output, then compares range values, rune slices, and UTF-8 rune counting.
- Examples
- Contrasts the three-byte `汉` with loops over `hêllo` that print a byte, a rune, or rune-slice positions.
- What you can do after
- Diagnose/debug with it: distinguish byte lengths and offsets from rune counts and positions, then select the appropriate iteration or conversion.
Read how 100 Go Mistakes and How to Avoid Them explains rune →
Go in Practice, Second Edition
A rune is Go's integer type for representing a Unicode code point.
- How it is used
- Uses runes to make string processing handle multibyte, non-ASCII characters correctly.
- How deep it goes
- Defines the Unicode-code-point type and demonstrates conversion to []rune, stopping short of deeper Unicode internals.
- Examples
- Demonstrates reversing an ASCII name and a name containing a non-ASCII character, then validating the fix with go test.
- What you can do after
- Diagnose and fix character-processing bugs by converting strings to rune slices before character-wise operations.
Learn Go with Pocket-Sized Projects
A rune is Go's value type representing a single Unicode code point.
- How it is used
- Uses runes to represent individual Unicode code points and inspect multilingual strings.
- How deep it goes
- Defines rune literals and demonstrates iteration, then stops short of treating grapheme-like character units as native runes.
- Examples
- Uses '學', multilingual greetings, and the नमस्त string to contrast rune literals, strings, and combining marks.
- What you can do after
- Apply rune literals and []rune iteration, or choose Unicode normalization when code points do not match desired character units.
Read how Learn Go with Pocket-Sized Projects explains rune →
Go in Action, Second Edition
A rune is Go's alias for int32 that represents a Unicode code point independently of its encoded representation.
- How it is used
- Uses rune for Unicode-aware string iteration, character comparison, conversion, and inspection.
- How deep it goes
- Defines the int32 alias, demonstrates range and []rune conversion, and applies Unicode packages without detailing their full APIs.
- Examples
- Demonstrates 地鼠 iteration, []rune indexing, and À classification, case conversion, and encoded-length inspection.
- What you can do after
- Apply it via range loops and Unicode packages to process, classify, compare, and inspect characters.
Related concepts
- code pointequivalent to · A code point is a numeric value assigned by a character-representation standard to identify an abstract character or symbol.
- int32kind of · An int32 is a signed integer type represented using exactly 32 bits.
- bytescontrasts with · Bytes are an ordered sequence of values, each conventionally eight bits, used to represent binary data.
- range loopused by · A range loop is a Go for-loop form that iterates over values or entries produced by a supported rangeable expression.
- slicingpart of · Slicing selects or partitions a portion of an indexed sequence or multidimensional array, often along specified indices or dimensions.
- byte typecontrasts with · A byte type is a fixed-width integer type occupying eight bits, with signedness and numeric range determined by the language.
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