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Microsoft KB Archive/38291

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Knowledge Base


INFO: Cannot Define Other Preprocessor Directives with #define

Article ID: 38291

Article Last Modified on 7/5/2005



APPLIES TO

  • Microsoft C/C++ Professional Development System 7.0
  • Microsoft C Professional Development System 6.0a
  • Microsoft C Professional Development System 6.0a
  • Microsoft Visual C++ 1.0 Professional Edition
  • Microsoft Visual C++ 1.5 Professional Edition
  • Microsoft Visual C++ 1.0 Professional Edition
  • Microsoft Visual C++ 2.0 Professional Edition
  • Microsoft Visual C++ 4.0 Standard Edition
  • Microsoft Visual C++ 5.0 Standard Edition
  • Microsoft Visual C++ 6.0 Service Pack 5



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 ];
}
                


Additional query words: 8.00 8.00c 9.00

Keywords: kbinfo kbcompiler KB38291