1.6.1 New Type

• Add three new types " long long", "char16_t" and "char32_t".
• New container: forward_list, unordered_map unordered_set. The latter two support implementing hash tables.
• nullptr is always a pointer type, Don’t use NULL any more. NULL is just 0 In C language, but in strong type C++ language, NULL can be ambiguity in f(int); and f(foo *);
• Syntactic improvement of C++ 14:
  1. Prefix 0b and are followed by binary digits.
  2. To use the single quote character, making the million dollar value render in C++ as: 1’000’000.00.
    int val = 0b11110000; 
    std::cout << 0b1000’0001’1000’0000; 
  ␣␣std::cout<<300’000.00;
• Note that the syntax of C++ attribute-tokens might seem a bit unfamiliar. The list of attributes, including [[deprecated]], comes after keywords like class or enum, and before the entity name.
  class [[deprecated]] flaky { 
  }; 
  [[deprecated("Consider␣using␣something␣other␣than␣cranky")]] 
  int cranky(){ 
     return 0; 
  } 
   
  // below two statements produce compiler warning 
    flaky f; 
    return cranky();