StackOverflow 文档 Embarcadero Delphi 教程 字符串 字符串 字符串 Created: November-22, 2018 uses System.Character; var S1, S2: string; begin S1 := 'Foo'; S2 := ToLower(S1); // Convert the string to lower-case S1 := ToUpper(S2); // Convert the string to upper-case 个字符参考计数