how to tell if a character is upper case dart code example

Example: dart char is uppercase

import 'dart:io';

main() {
  print("Enter a string : ");
  var str = stdin.readLineSync();

  if (str[0].toUpperCase() == str[0]) {
    print("The first character is uppercase");
  } else {
    print("The first character is not uppercase");
  }
}