P-Code Applications Must Have MPC Used on Them

The information in this article applies to:

• Microsoft C/C++ for MS-DOS, version 7.0
• Microsoft Visual C++ for Windows, version 1.0 and 1.5

SUMMARY

The /Oq switch tells the compiler to generate packed code (p-code). After the p-code program is linked, the Make P-Code utility (MPC) must be used to make the program runnable. If MPC is not used on the p-code program, depending on the program type and the host environment, different error messages will be displayed when the program is executed.

NOTE: In Microsoft C/C++ Compiler version 8.0, the linker automatically detects when you are creating a p-code application and automatically runs MPC.EXE. This means that there is no need to use the /PCODE linker switch or to separately run MPC.EXE.

MORE INFORMATION

Attempting to run an MS-DOS p-code executable that hasn't had MPC used on it may cause MS-DOS to display the following message:

   This program cannot be run in DOS mode.

Attempting to load a Windows dynamic-link library (DLL) that has been compiled into p-code but that has not had MPC run on it, can cause various problems ranging from UAEs to system hangs.

To make sure that a p-code executable or DLL is runnable, do one of the following:

• Compile and link in one step.

  If the /Oq option is specified without the /c option, the CL driver will automatically invoke MPC after the link has been completed.

  -or-

• Link with the /PCODE option.

  If the compile and link are done as separate steps, the /PCODE option can be used to tell the linker to invoke MPC after the link has completed.

  -or-

• Run MPC manually.

  MPC can be used directly on the executable or DLL that was created by the linker.

NOTE: If a Windows p-code application that has not had MPC used on it is run under MS-DOS, the following standard message will be displayed:

   This program requires Microsoft Windows.