assemblyunresolved-externalmasm32

unresolved external symbol _WinMainCRTStartup

I'm trying to assemble a simple "Hello world" application with Masm32. It assembles fine but when I try to link it, the linker says

LINK : error LNK2001: unresolved external symbol _WinMainCRTStartup prog1.exe : fatal error LNK1120: 1 unresolved externals

This is the source code of the program:

.586P

.MODEL FLAT, STDCALL
STD_OUTPUT_HANDLE equ -11

; Prototypes of external procedures
EXTERN GetStdHandle@4:NEAR
EXTERN WriteConsoleA@20:NEAR
EXTERN ExitProcess@4:NEAR

; INCLUDELIB directives for the linker
includelib c:\masm32\lib\user32.lib
includelib c:\masm32\lib\kernel32.lib

;============ data segment =================
_DATA SEGMENT
HANDL DWORD ?
BUFER DB "Hello world\n", 0
NUMB  DWORD ?
NUMW  DWORD ?
_DATA ENDS

_TEXT SEGMENT
MAIN:
;====== Get the output handle ======
     PUSH STD_OUTPUT_HANDLE
     CALL GetStdHandle@4
     MOV  HANDL, EAX


; Output the buffer contents to the console
     PUSH 0
     PUSH OFFSET NUMW
     PUSH NUMB
     PUSH OFFSET BUFER
     PUSH HANDL
     CALL WriteConsoleA@20

;Exit application
     PUSH 0
     CALL ExitProcess@4
_TEXT ENDS
END

I found in some forums that this is caused by the encode type. However it doesn't seem to matter to my problem

Solution

  • The linker assumes the default name for entry point. You have a few options.
    1. Use the C libraries on the platform, which because you're using MASM, I assume you don't want to.
    2. Rename your MAIN to _WinMainCRTStartup
    3. Use "-entry:MAIN" on the Link.exe command-line (you may need a "public MAIN" line)