Q65306: toupper() Gives C4135 Warning

Article: Q65306
Product(s): See article
Version(s): 6.00   | 6.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | s_quickc s_quickasm | mspl13_c
Last Modified: 31-AUG-1990

When compiling a function that contains a call to toupper() in the
format

   char toupper (char)

at warning level 2 or above, the compiler will generate the following
warning message:

   C4135: Conversion between two integral types

Since the ANSI-standard draft of December 7, 1988, specifies the
syntax for this function as follows, the warning is in compliance with
the standard:

   int toupper (int)