slice method

String slice({ int? start, int? end, int step = 1, })

Returns a new string containing the characters of this from start inclusive to end exclusive, skipping by step.

Example:

'word'.slice(start: 1, end: 3); // 'or'
'word'.slice(start: 1, end: 4, step: 2); // 'od'

start defaults to the first character if step is positive and to the last character if step is negative. end does the opposite.

Example:

'word'.slice(end: 2); // 'wo'
'word'.slice(start: 1); // 'ord'
'word'.slice(end: 1, step: -1); // 'dr'
'word'.slice(start: 2, step: -1); // 'row'

If start or end is negative, it will be counted backwards from the last character of this. If step is negative, the characters will be returned in reverse order.

Example:

'word'.slice(start: -2); // 'rd'
'word'.slice(end: -1); // 'wor'
'word'.slice(step: -1); // 'drow'

Any out-of-range values for start or end will be truncated to the maximum in-range value in that direction.

Example:

'word'.slice(start: -100); // 'word'
'word'.slice(end: 100); // 'word'

Will return an empty string if start and end are equal, start is greater than end while step is positive, or end is greater than start while step is negative.

Example:

'word'.slice(start: 1, end: -3); // ''
'word'.slice(start: 3, end: 1); // ''
'word'.slice(start: 1, end: 3, step: -1); // ''

Implementation

String slice({int? start, int? end, int step = 1}) {
  final indices = sliceIndices(start, end, step, this.length);
  if (indices == null) {
    return '';
  }

  final _start = indices.start;
  final _end = indices.end;
  final stringBuffer = StringBuffer();

  if (step > 0) {
    for (var i = _start; i < _end; i += step) {
      stringBuffer.write(this[i]);
    }
  } else {
    for (var i = _start; i > _end; i += step) {
      stringBuffer.write(this[i]);
    }
  }
  return stringBuffer.toString();
}