Dart Flutter：如何将字符串中的字符替换为数字（反之亦然）？

Question

例如，我想替换 A = 1、B = 2、C = 3 等和空字符 = /。

输出将是什么：

Enter a string: Hello world
Output: 8 5 12 12 15 / 23 15 18 12 4

反之亦然。 我环顾四周，但似乎无法得到令人满意的答案。

Answer 1

您可以将所有字符串放入映射中，然后在将字符串拆分为""后运行 for in 循环

对于前。 -

        Map<String, dynamic> myMap= {
            'A' : 1,
            'B' : 2,
            'C' : 3,
            'D' : 4,
            "E" : 5,
            "/" : " ",
          };
        
        String test =  "abcedadd/abcde";
        List<dynamic>chars =[];
    
        // Convert your string into list by call split method and run for in loop on every element     
       
       for (var element in test.split("")) {

       // Check if key is preset in map then return map value else you can set any default value like i put 0

           chars.add(myMap.containsKey(element.toUpperCase()) ? myMap[element.toUpperCase()] : 0 );
        }

       // Convert your list into string by joining by space use can use any value here
        print(chars.join(" "));

结果将是 1 2 3 5 4 1 4 4 1 2 3 4

Answer 2

也许这有帮助：

String myfunction(String input){
  final alpha= RegExp(r'^[a-zA-Z ]+$');
  final numeric= RegExp(r'^[0-9]+$');
  String output = '';
  const Map<String, String> lookupInt = {
    '1' :'a',
    '2' :'b',
    '3' :'c',
    '4' :'d',
    '5' :'e',
    '6' :'f',
    '7' :'g',
    '8' :'h',
    '9' :'i',
    '10':'j',
    '11':'k',
    '12':'l',
    '13':'m',
    '14':'n',
    '15':'o',
    '16':'p',
    '17':'q',
    '18':'r',
    '19':'s',
    '20':'t',
    '21':'u',
    '22':'v',
    '23':'w',
    '24':'x',
    '25':'y',
    '26':'z',
    '/' :' '
  };
  Map<String, String> lookupChart =  lookupInt.map((k, v) => MapEntry(v, k));
  if(alpha.hasMatch(input)){
    output = input.toLowerCase().split('').map((e) => lookupChart[e]??'').join('');
  }
  if(numeric.hasMatch(input)){
    output = input.toLowerCase().split('').map((e) => lookupInt[e]??'').join('');
  }
  return output;
}

Answer 3

另一种方法可能是使用String的runes方法，它返回字符的整数值的Itterable 。 在 map 中查找那些转换回 String 的内容是可行的，但如果一个字符不存在，则 Map 将返回 null，我们可以将其替换为 epty 字符串或其他字符串。

theUCString.runes.forEach(
(c) => theOutput +=" ${charsMap[String.fromCharCode(c)] ?? ""}");

//setting things up 
  String theInput = "Hello world";
  String theUCString = theInput.toUpperCase();
  String theOutput = "";
  Map<String, String> charsMap = Map();
  
// build a lookup map  
  for (int i = 1; i <= 26; i++) {
    String char = String.fromCharCode(i + 64);
    charsMap[char] = (i).toString();
  }
  charsMap[" "] = "/";

// Now with that...
// We'll use each character from input's runes, integer values representing that UTF16 character
// If the character key doesn't exist it will return null, which we'll make an empty string

  theUCString.runes.forEach(
      (c) => theOutput += " ${charsMap[String.fromCharCode(c)] ?? ""}");

  print("Output: $theOutput");

Answer 4

尝试这样的事情

  String s = "hello";
  for (var c in s.split('')) {
    print(c.codeUnitAt(0) - 'a'.codeUnitAt(0));
  }
  
  List<int> numbers = [7, 4, 11, 11, 14];
  for (var n in numbers) {
    print(String.fromCharCode(n + 'a'.codeUnitAt(0)));
  }