INFO: Cannot Define Other Preprocessor Directives with #define (38291)



The information in this article applies to:

  • Microsoft C/C++ for MS-DOS 7.0
  • Microsoft C for MS-DOS
  • Microsoft C for OS/2
  • Microsoft Visual C++ for Windows, 16-bit edition 1.0
  • Microsoft Visual C++ for Windows, 16-bit edition 1.5
  • Microsoft Visual C++, 32-bit Editions 1.0
  • Microsoft Visual C++, 32-bit Editions 2.0
  • Microsoft Visual C++, 32-bit Editions 4.0
  • Microsoft Visual C++, 32-bit Editions 5.0
  • Microsoft Visual C++, 32-bit Editions 6.0

This article was previously published under Q38291

SUMMARY

The Microsoft C Compiler does not allow a "#define" statement to define another preprocessor directive. Although the preprocessor output option (/P or /E) generates the desired expansion, the Microsoft C Compiler generates the following error messages when compiling the code below:
error C2014: preprocessor command must start as first non-whitespace
error C2054: expected '(' to follow 'define'
error C2061: syntax error : identifier 'MAX'
Microsoft C/C++ for Windows NT, version 8.0, generates the following errors on the code shown below:
error C2014: preprocessor command must start as first nonwhite space
error C2065: 'MAX' : undeclared identifier
error C2057: expected constant expression
The Microsoft C/C++ compiler included with Visual C++, 32-bit edition, version 4.0, generates the following errors on the code shown below:
error C2121: '#' : invalid character : possibly the result of a macro expansion
error C2282: 'define' is followed by 'MAX' (missing ','?)
The Microsoft C/C++ compiler included with Visual C++, 32-bit edition, versions 5.0 and 6.0, generates the following errors on the code shown below:
error C2121: '#' : invalid character : possibly the result of a macro expansion
error C2146: syntax error : missing ';' before identifier 'MAX'
error C2501: 'define' : missing storage-class or type specifiers
fatal error C1004: unexpected end of file found

Sample Code

The following code demonstrates the problem:
/* Compile options needed: none
*/ 

#define A( x )      x##define       MAX     100

A( # )
/*
    Preprocessor output expands A( # ) to be:
#define       MAX     100
*/ 

char w[ MAX ];
void main(void);
void main()
{
   w[ 0 ] = w[ MAX ];
}
				

Modification Type:MinorLast Reviewed:7/5/2005
Keywords:kbCompiler kbinfo KB38291