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[Golang] 文字列操作サンプル

Last updated at Posted at 2018-11-18

はじめに

Golangの文字列操作をまとめました。バージョンは1.11.2で確認しました。

ソース:sample_strings.go

文字列の結合

  s := "ABCDEFG"
  s = s + "hijklmn"
  fmt.Println(s) // -> "ABCDEFhijklmn"

文字列の 大文字、小文字変換

  s = "ABCDEFGhijklmn"
  fmt.Println(strings.ToUpper(s))  // -> "ABCDEFHIJKLMN"
  fmt.Println(strings.ToLower(s))  // -> "abcdefhijklmn"

文字列の部分取得

  s = "ABCDEFGhijklmn"
  fmt.Println(s[4:10]) // -> "EFGhij"
  fmt.Println(s[4:])   // -> "EFGhijklmn"
  fmt.Println(s[:10])  // -> "ABCDEFGhij"
  fmt.Println(s[:])    // -> "ABCDEFGhijklmn"

両端トリム

  s = "    123456    "
  fmt.Printf("[%s]\n", strings.TrimSpace(s)) // -> "[123456]"

両端トリム(トリム対象指定)

  s = "    123456    "
  fmt.Printf("[%s]\n", strings.Trim(s, " ")) // -> "[123456]"

左側トリム、右側トリム

  s = "    123456    "
  fmt.Printf("[%s]\n", strings.TrimLeft(s, " "))  // -> "[123456    ]"
  fmt.Printf("[%s]\n", strings.TrimRight(s, " ")) // -> "[    123456]"

文字列中に指定文字列が含まれているか

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.Contains(s, "Delta")) // -> true

文字列中の指定文字列の出現位置

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.Index(s, "Delta")) // -> 19
  fmt.Println(strings.Index(s, "Hotel")) // -> -1

文字列中の指定文字列の最後の出現位置

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.LastIndex(s, "a")) // -> 23

文字列中の指定文字列のカウント

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.Count(s, "a")) // -> 4

文字列の先頭一致

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.HasPrefix(s, "Alfa")) // -> true

文字列の後方一致

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(strings.HasSuffix(s, "Golf")) // -> true

文字列置換

  s = "hogehogehogehoge"
  fmt.Println(strings.Replace(s, "ge", "ji", 2)) // -> "hojihojihogehoge" 最後の引数は回数
  fmt.Println(strings.Replace(s, "ge", "ji", -1)) // -> "hojihojihojihoji" -1で無制限

文字列繰り返し

  s = "abc"
  fmt.Println(strings.Repeat(s, 3)) // -> "abcabcabc"

文字列のタイトルケースへの変換

  s = "alfa bravo charlie delta echo foxtrot golf"
  fmt.Println(strings.Title(s)) // -> "Alfa Bravo Charlie Delta Echo Foxtrot Golf"

文字列の分割

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  slice := strings.Split(s, " ")
  for _, str := range slice {
    fmt.Printf("[%s]", str) // -> [Alfa][Bravo][Charlie][Delta][Echo][Foxtrot][Golf]
  }

文字列結合

  slice = []string{"Alfa", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf"}
  fmt.Println(strings.Join(slice, ",")) // -> "Alfa,Bravo,Charlie,Delta,Echo,Foxtrot,Golf"

文字列長カウント

  s = "Alfa Bravo Charlie Delta Echo Foxtrot Golf"
  fmt.Println(len(s)) // -> 42

文字列長カウント(マルチバイト)

  s = "Go言語"
  fmt.Println(len(s))         // -> 8
  fmt.Println(len([]rune(s))) // -> 4

複数行文字列

  s = `
  This is a sample.
  golang multiple lines.
  `
  fmt.Println(s) /* ->
  This is a sample.
  golang multiple lines.
  */

文字列の整数変換

  s = "123"
  si, _ := strconv.Atoi(s)
  si = si + 1
  fmt.Println(si) // -> 124

文字列の浮動小数変換

  s = "123.456"
  sf, _ := strconv.ParseFloat(s, 64)
  sf = sf + 0.1
  fmt.Println(sf) // -> 123.556
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