🔤 Strings

👀 Fast Lookup

UTF-8 encoding: Go strings use UTF-8, 1-4 bytes per character
rune: Alias for int32, represents a single UTF-8 character
len() vs character count: len() returns bytes, not character count
Character count: Use len([]rune(str)) to get actual character count
Range iteration: Use range to iterate over runes, not bytes
Immutable: Strings are read-only slices of bytes
Internal structure: String = pointer + length (like slice header)
Copy behavior: Copying strings copies pointer and length, not underlying bytes

In this note, I will just list down the things I need to remember about strings in Go.

Go use "UTF-8" encoding for strings. And a single UTF-8 needs 1 to 4 bytes to represent.
- Go use rune (alias for int32) to represent a single character in a string.
len() returns the number of bytes in a string.
To get the number of actual characters in a string, use []rune to convert the string to a slice of runes.

func main() {
  str := "안녕, World!"
  fmt.Println(len(str)) // 12
  fmt.Println(len([]rune(str))) // 11
}

func main() {
  str := "안녕, World!"
  for i, r := range str {
    fmt.Println(i, r)
  }
}

String in Go is a read-only (immutable) slice of bytes.
- "read-only" means the bytes cannot be modified.

type StringHeader struct {
  Data uintptr
  Len int
}