ID Number: Q38730
4.00 5.00 5.10 6.00 6.00a 6.00ax 7.00 | 5.10 6.00 6.00a
MS-DOS | OS/2
Summary:
In Microsoft C versions 5.1, 6.0, 6.0a, 6.0ax, and C/C++ version 7.0,
there is no compiler switch that changes the default int to long rather
than short. Including a "typedef long int;" or a "#define int long" in
each and every module you compile, will resolve some of the problems.
However, redefining the identifier "int" may cause severe and
difficult-to-find problems. Microsoft emphatically does NOT recommend
it.
Note: K & R and ANSI are both very clear that int could be any size,
provided that it's at least 16 bits. It is bad coding practice to rely
on 32-bit ints because it makes porting code difficult.
Changing all int variables to long causes your program to run very
slowly because whenever it does arithmetic, it will have to do slower
32-bit arithmetic rather than the more efficient built-in 16-bit
arithmetic. This situation is true even on 80386 processors because
current versions of Microsoft's compilers do not support the
generation of code that takes advantage of the 80386's 32-bit
registers.
A better strategy is to change to long only the variables that need to
be long, which will avoid many unintended side effects, and prevent
unnecessary 32-bit arithmetic.
Additional reference words: 5.10 6.00 6.00a 6.00ax 7.00