greaterThanDecString method
Relational greater than operator. 判断a是否大于b
Implementation
bool greaterThanDecString(String a, String b) {
final aDecimal = _safeParseDecimal(a);
final bDecimal = _safeParseDecimal(b);
if (aDecimal == null || bDecimal == null) return false;
return aDecimal > bDecimal;
}