Table of Contents
This part deals with the functions called and objects created automatically during the course of a program's existence.
While we can't reproduce the contents of the Standard here (you need to get your own copy from your nation's member body; see our homepage for help), we can mention a couple of changes in what kind of support a C++ program gets from the Standard Library.
C++ has the following builtin types:
char
signed char
unsigned char
signed short
signed int
signed long
unsigned short
unsigned int
unsigned long
bool
wchar_t
float
double
long double
These fundamental types are always available, without having to include a header file. These types are exactly the same in either C++ or in C.
Specializing parts of the library on these types is prohibited: instead, use a POD.
    The header limits defines
    traits classes to give access to various implementation
    defined-aspects of the fundamental types. The traits classes --
    fourteen in total -- are all specializations of the template class
    numeric_limits, documented here
    and defined as follows:
    
   template<typename T>
     struct class
     {
       static const bool is_specialized;
       static T max() throw();
       static T min() throw();
       static const int digits;
       static const int digits10;
       static const bool is_signed;
       static const bool is_integer;
       static const bool is_exact;
       static const int radix;
       static T epsilon() throw();
       static T round_error() throw();
       static const int min_exponent;
       static const int min_exponent10;
       static const int max_exponent;
       static const int max_exponent10;
       static const bool has_infinity;
       static const bool has_quiet_NaN;
       static const bool has_signaling_NaN;
       static const float_denorm_style has_denorm;
       static const bool has_denorm_loss;
       static T infinity() throw();
       static T quiet_NaN() throw();
       static T denorm_min() throw();
       static const bool is_iec559;
       static const bool is_bounded;
       static const bool is_modulo;
       static const bool traps;
       static const bool tinyness_before;
       static const float_round_style round_style;
     };
   
     The only change that might affect people is the type of
     NULL: while it is required to be a macro,
     the definition of that macro is not allowed
     to be (void*)0, which is often used in C.
    
     For g++, NULL is
     #define'd to be
     __null, a magic keyword extension of
     g++.
    
     The biggest problem of #defining NULL to be
     something like “0L” is that the compiler will view
     that as a long integer before it views it as a pointer, so
     overloading won't do what you expect. (This is why
     g++ has a magic extension, so that
     NULL is always a pointer.)
    
In his book Effective
      C++, Scott Meyers points out that the best way
    to solve this problem is to not overload on pointer-vs-integer
    types to begin with.  He also offers a way to make your own magic
    NULL that will match pointers before it
    matches integers.
    
See the Effective C++ CD example.