CODEWITHSUNDEEP
dart
joisberg
joisberg

Reputation: 187

Remove words except last one in String

I have a String with different value every time:

String words = "My name is Rob Joe";

I want to get only last word

Joe

but every time I don't know how many words the string consists of

Upvotes: 0

Views: 203

Answers (4)

lrn
lrn

Reputation: 71903

If you want to find the last word, you should first properly define what a "word" is.

It's clearly obvious here, which is why it's doubly important to write it down, because something else may be just as obvious to someone else. (Read: Nothing is obvious. Document it all!)

But let's say that a word is a maximal contiguous sequence of ASCII letters. Then that's what you should look for.

Splitting on space characters works for this string, but won't if you have punctuation, or trailing whitespace, or any number of other complications.

I'd probably use a RegExp:

  // Matches a word. If used properly, only matches entire words.
  var wordRE = RegExp(r"[a-zA-Z]+"); 
 
  // Assume at least one word in `words`. Otherwise need more error handling.
  var lastWord = wordRe.allMatches(words).last[0]!;

This can be a little inefficient, if the string is long. Another approach that might be more efficient, depending on the RegExp implementation, is to search backwards:

  /// Captures first sequence of [a-zA-Z]+ looking backwards from end.
  var lastWordRE = RegExp(r"$(?<=([a-zA-Z]+)[^a-zA-Z]*)");

  var lastWord = lastWordRE.firstMatch(words)?[1]!;

If you don't want to rely on RegExps (which are admittedly not that readable, and their performance is not always predictable), you can search for letters manually:

  String? lastWord(String words) {
    var cursor = words.length;
    while (--cursor >= 0) {
      if (_isLetter(words, cursor)) {
        var start = 0;
        var end = cursor + 1;
        while (--cursor >= 0) {
          if (!_isLetter(words, prev)) {
            start = cursor + 1;
            break;
          }
        }
        return words.substring(start, end);
      }
    }
    return null;
  }
   
  bool _isLetter(String string, int index) {
    var char = string.codeUnitAt(index) | 0x20; // lower-case if letter.
    return char >= 0x61 /*a*/ && char <= 0x7a /*z*/;
  }

But first of all, decide what a word is.

Some very real words in common sentences might contain, e.g., ' or -, but whether they matter to you or not depends on your use-case. More exotic cases may need you to decide whether"e.g." is one word or two? Is and/or? Is i18n? Depends on what it'll be used for.

Upvotes: 0

Dennis Kaselow
Dennis Kaselow

Reputation: 4551

Instead of splitting, you can also use substring and lastIndexOf:

final words = "My name is Rob Joe";
final lastWord = words.substring(words.lastIndexOf(" ") + 1);
print(lastWord);

Upvotes: 0

Ahmed Sbai
Ahmed Sbai

Reputation: 16259

String words = "My name is Rob Joe";
var array = words.split(" "); // <-- [My, name, is, Rob, Joe]
print(array.last); // output 'Joe'

Upvotes: 1

Munsif Ali
Munsif Ali

Reputation: 6259

In Flutter(Dart), you can get the last word of a string by splitting the string into an array of substrings using the split method and then accessing the last element of the resulting array. Here's an example:

   String words = "My name is Rob Joe";
   List<String> wordsArray = myString.split(" ");
   String lastWord = wordsArray[wordsArray.length - 1];
   print(lastWord); // "Joe"

Upvotes: 1

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