isNumber method

bool isNumber(
  1. String st
)

Is the string a number?

st The string. Returns true, if the input string is a number.

Implementation

bool isNumber(String st) {
  if (st[0] == _minusSign && st.length == 1) {
    return false;
  }
  if (st[0] == "+" && st.length == 1) {
    return false;
  }
  if (st[0] == _decimalSeparator && (st.length == 1 || !isDigit(st[1]))) {
    return false;
  }
  if (st[0] == 'e' || st[0] == 'E') {
    return false;
  }
  for (int i = 0; i < st.length; i++) {
    String ch = st[i];

    if (!isDigit(ch) &&
        ch != _minusSign &&
        ch != _decimalSeparator &&
        ch != 'e' &&
        ch != 'E' &&
        ch != "+") {
      return false;
    }
  }

  return true;
}