insertSeparator static method
插入分隔符 Insert separator
Implementation
static String insertSeparator(String str, {int interval = 4, String separator = ' '}) {
final result = StringBuffer();
for (int i = 0; i < str.length; i++) {
if (i > 0 && i % interval == 0) {
result.write(separator);
}
result.write(str[i]);
}
return result.toString();
}