Metasize

C++ defines signed and unsigned variants of the types char, short, int, long, but does not define their sizes. Occasionally, knowing their sizes is useful -- or, more often, knowing which of them is a particular size is useful.

Here are three portable examples of how to use C and C++ type information to determine 8-, 16-, 32-, and 64-bit signed and unsigned types, if they exist. They rely upon the following guarantees of ISO C++:

• sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long)
• SCHAR_MAX >= 127 (2^7 - 1)
• SHRT_MAX >= 32767 (2^15 - 1)
• INT_MAX >= 32767 (2^15 - 1)
• LONG_MAX >= 2147483647 (2^31 - 1)

• metasize.cpp (4694 bytes, last modified 07/29/2003 12:20:19 PM PDT)
  template metaprogramming version
• preprosize.cpp (2958 bytes, last modified 07/29/2003 12:20:20 PM PDT)
  templates + conditional compilation version
• macrosize.c (3466 bytes, last modified 07/29/2003 12:20:19 PM PDT)
  macro metaprogramming version