How can you work with strings in Go?

Strings in Go are immutable sequences of bytes. They can represent both UTF-8 text and arbitrary binary data.

Main ways to work with them:

• Declaration and initialization:

  var s1 string           // Empty string
  s2 := "hello"          // Initialized with a string literal
  s3 := `multiline
  string`                 // Raw string literal
  

• String length:

  len(s2) // Length in bytes. For "hello" it will be 5.
  

• Access to bytes:

  b := s2[0] // Get byte at index. Returns 'h' (in UTF-8).
  

  Direct access to bytes does not guarantee getting a UTF-8 character.

• Access to runes (UTF-8 characters): Strings can be iterated over runes:

  for index, runeValue := range s2 {
      fmt.Printf("Index: %d, Rune: %c\n", index, runeValue)
  }
  

  Length in runes:

  utf8.RuneCountInString(s2) // Length in runes. For "hello" it will be 5.
  

• String concatenation:

  str1 := "hello"
  str2 := " world"
  result := str1 + str2 // Concatenation with + operator
  

  For efficient concatenation of many strings, use strings.Builder.

  var sb strings.Builder
  sb.WriteString("hello")
  sb.WriteString(" ")
  sb.WriteString("world")
  result := sb.String() // Get the resulting string
  

• Conversion between strings and byte/rune slices:

  byteslice := []byte(s2)   // String to byte slice
  rs := []rune(s2)          // String to rune slice
  
  backToString := string(byteslice) // Byte slice to string
  backToString = string(rs)         // Rune slice to string
  

• strings package: Provides many useful functions:

  • Contains, HasPrefix, HasSuffix
  • Index, LastIndex
  • Replace, ToUpper, ToLower, Trim, TrimSpace
  • Split, Join

• strconv package: For converting strings to other data types (numbers, booleans) and vice versa.

  i, err := strconv.Atoi("123") // String to int
  s := strconv.Itoa(456)        // Int to string
  

• Immutability: Any operations that seem to modify a string (like concatenation) actually create a new string. This is important to consider for performance when making frequent modifications. In such cases, it's better to use []byte or strings.Builder.