Max Identifier Length May Cause Mixed C/MASM Conflict (70249)


The information in this article applies to:

  • Microsoft Macro Assembler (MASM) 5.1
  • Microsoft Macro Assembler (MASM) 5.1a
This article was previously published under Q70249

SUMMARY

The Microsoft Macro Assembler (MASM) versions 5.1 and 5.1a allow identifiers to have a length of 31 characters. The Microsoft C Compiler versions 5.1, 6.0, and 6.0a also allow identifiers to have a length of up to 31 characters. However, the C compiler adds an implied leading underscore, which may make the total length of an identifier 32 characters.

The above limits may cause a problem when performing mixed-language programming where a C identifier that is 31-characters long needs to be recognized by a Macro Assembler module. The C identifier of 31 characters becomes 32 characters because of the added leading underscore, and the assembler can only recognize 31 characters. If this occurs, a "L2029: unresolved external" error will be generated by the linker when it does not locate a symbol with the truncated name.

MORE INFORMATION

To get the assembler routine to match the C identifier of 31 characters, you can do one of the following:

  1. Use the .MODEL directive and specify the C language type. For example: 
          .MODEL small,c  ; The C language type specifies C conventions
    The C language type specifies C naming and calling conventions. It will allow the use of a 31-character identifier and also add the implied leading underscore.
  2. Modify the C program to shorten the length of the variable's name.
  3. Update to Macro Assembler version 6.0. Identifiers may be up to 247 characters long with version 6.0.
Modification Type:MajorLast Reviewed:10/29/2003
Keywords:KB70249
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