Call C standard library function from asm in Visual Studio

Microsoft refactored much of the C runtime and libraries in VS 2015. Some functions are no longer exported from the C library (some are defined in a C header file). Microsoft has some compatibility libraries like legacy_stdio_definitions.lib and legacy_stdio_wide_specifiers.lib, but you can also choose to use the older Visual Studio 2013 platform toolset with the older C libraries.

To change the platform toolset: pull down the Project menu; select Properties...; go to Configuration Properties/General, and change Platform Toolset to Visual Studio 2013 (v120)

It appears that it' possible to use the Visual Studio 2015 Toolset with a few modifications.

• You'll need to add these libraries to your dependencies: libcmt.lib, libvcruntime.lib, libucrt.lib, legacy_stdio_definitions.lib. Alternatively you could use includelib to include these libraries in your assembly file.
• Specify C calling convention for your main procedure using PROC C
• At the end of your file (and this is important) do not use end main, use end only. Not fixing this may cause unexpected crashes.
• Although we can use ExitProcess to exit our application, we can also put the return code in EAX and do a ret to return. The C runtime calls our main function, and will call the shutdown code for us upon returning.

The code could look like:

.586
.model flat, stdcall
option casemap:none

includelib libcmt.lib
includelib libvcruntime.lib
includelib libucrt.lib
includelib legacy_stdio_definitions.lib

ExitProcess PROTO return:DWORD
extern printf:NEAR

.data
text BYTE "Text", 0

.code
main PROC C                    ; Specify "C" calling convention
    push offset text
    call printf
    add  esp, 4
;   invoke ExitProcess,0       ; Since the C library called main (this function)
                               ; we can set eax to 0 and use ret`to have
                               ; the C runtime close down and return our error
                               ; code instead of invoking ExitProcess
    mov eax, 0
    ret
main ENDP
end                            ; Use `end` on a line by itself
                               ; We don't want to use `end main` as that would
                               ; make this function our program entry point
                               ; effectively skipping by the C runtime initialization