创建字符串

要创建一个字符串，我们可以使用单引号或双引号或三引号：

void main() {
  String a = 'abc'; //单引号
  String b = "abc"; //双引号
  //三引号
  String c = ''' 
        abc
        def
          ''';
}

字符串拼接

多个字符串可使用 + 号进行拼接

void main() {
  String a = 'abc';
  String b = "abc";
  print(a + b);
}

获取单个字符

可使用下标的方式获取单个字符

void main() {
  String a = 'abc';
  print(a[1]);
}

常用的属性

void main() {
  String a = 'abcdefg';

  print(a.codeUnits); 
  print(a.hashCode);
  print(a.isEmpty);
  print(a.isNotEmpty);
  print(a.length);
  print(a.runes);
  print(a.runtimeType);
  //执行结果
  //[97, 98, 99, 100, 101, 102, 103]
  //180814200
  //false
  //true
  //7
  //(97, 98, 99, 100, 101, 102, 103)
  //String
}

常用的属性

void main() {
  String a = '  abacdfefg  ';

  print(a.codeUnitAt(0));
  print(a.compareTo('other'));
  print(a.contains('b'));
  print(a.endsWith('f'));
  print(a.indexOf('a'));
  print(a.lastIndexOf('f'));
  print(a.padLeft(20, '0'));
  print(a.padRight(20, '0'));
  print(a.replaceAll(r'a', 'h'));
  print(a.replaceAllMapped(r'a', (d) => d.hashCode.toString()));
  print(a.replaceFirst(r'a', 'h'));
  print(a.replaceFirstMapped(r'a', (d) => d.hashCode.toString()));
  print(a.replaceRange(0, 5, 'h'));
  print(a.split(r'f'));
  print(a.splitMapJoin(r'f'));
  print(a.startsWith(r'f', 2));
  print(a.substring(2, 6));
  print(a.toLowerCase());
  print(a.toUpperCase());
  print(a.trim());
  print(a.trimLeft());
  print(a.trimRight());

//输出结果
//32
//-1
//true
//false
//2
//9
//0000000  abacdfefg
//  abacdfefg  0000000
//  hbhcdfefg
//  336578979b372031767cdfefg
//  hbacdfefg
//  994399439bacdfefg
//hcdfefg
//[  abacd, e, g  ]
//  abacdfefg
//false
//abac
//  abacdfefg
//  ABACDFEFG
//abacdfefg
//abacdfefg
//  abacdfefg
}