I got the error: undefined reference to WinMain when converting a simple matlab function to a c executable

Using coder to generate c executable result in an error. Here is part of the Matlab verbose

C:/crossdev/src/etc.. undefined reference to WinMain collect2.exe: error: 1d returned 1 exit status gmake: * [c:/temp/prodtest.exe] error 1 the make command returned an error of 2 An_error_occured_during_the_call_to_make is not recognized as an internal or external command, operable program or batch file

Error(s) encountered while building "prodtest' ### Failed to generate all binary outputs.

Strangely, Matlab is looking at c:/crossdev/src... but the crossdev folder does not exist on my machine. In short, Matlab is able to generate the c++ code but not the executable

[Hans Scharler]

Do you have a main.c file and a supported compiler installed (like, MATLAB Support for MinGW-w64 C/C++ Compiler )?

[Sylvain Gauthier]

This was the problem, I had no main.c file. Thanks for the reply.

[mr loop]

Try to save the file before running.

[rezvan rafiee alavi]

Ho did you create and use main.c file? because I made one but still I get the same error message

Answer 1

[upol]

https://uk.mathworks.com/help/coder/ug/standalone-c-c-executables-from-matlab-code.html

Answer 2

[Tom Courtney]

Hi as Quinghua said you should generate the C/C++ code first and then generate the exe. BUT before you generate the exe I think you need to make sure your setting will compile the main.c/main.h files in the examples folder.

1. Go to "more settings" under the generation step of the coder app

2. Search "main" under "all settings"

3. Under "generate example main" set the value to "generate and compile an example main function" (see image above)

[Tom Courtney]

Enlarge attached images by opening image in new tab

Answer 3

[upol]

I am trying to convert this simple code into excutable using matlab coder.

function y = hello_world 
%#codegen
y = 'Hello World!';

converting to source code C works but when i change the build type to Executable

It gives me this error:

Build error: C compiler produced errors. See the Build Log for further details.

C:/PROGRA~3/MATLAB/SUPPOR~1/R2018b/3P778C~1.INS/MINGW_~1.INS/bin/../lib/gcc/x86_64-w64-mingw32/6.3.0/../../../../x86_64-w64-mingw32/lib/../lib\libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text.startup+0x2e): undefined reference to `WinMain'

collect2.exe: error: ld returned 1 exit status

gmake: *** [C:/dummy/hello_world.exe] Error 1

The make command returned an error of 2

'An_error_occurred_during_the_call_to_make' is not recognized as an internal or external command,

operable program or batch file.

Error(s) encountered while building "hello_world":

### Failed to generate all binary outputs.

[Ben Knight]

same problem here. "undefined reference to `WinMain". I can create the C files, but not an executable. I am on 2017b... not suppose to be a problem. I installed via the add-on manager in MATLAB without errors.

Here are some responses from the command window that I get:

mex -setup

ans = MEX configured to use 'MinGW64 Compiler (C)' for C language compilation.

getenv('MW_MINGW64_LOC')

ans = 'C:\ProgramData\MATLAB\SupportPackages\R2017b\3P.instrset\mingw_w64.instrset'

Answer 4

[upol]

Why this gives problem in C Coder. Error: Directly accessing field or property of nonscalar struct or object not supported for code generation.

s1=string({OPS_FLT(:).ACFT_ID})

s2=OPS_FLT(2).ACFT_ID

uuindex=find(strcmpi(s1,s2))

({OPS_FLT(:).ACFT_ID}) has already been defined as

OPS_FLT(1).ACFT_ID="apple"

OPS_FLT(2).ACFT_ID="orange"

I am trying to find orange from the array. It works in Matlab but not in C Coder

Answer 5

[Qinghua Peng]

most probably, you shoud RTFM cited by @upol

according to the manual, you should generate code file first, then generated a main.c and main.h that satisfied your apps based on the generated example/main.c and example/main.h

finally, you should run the prj file again, add Additional source files and Additional include directories, Generate.

Answer 6

[Ayush]

Hi @Sylvain Gauthier

Although I do not have access to your file but I was also getting the same error when using 'mexFuntion' as entry point. 

#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <engine.h>
#include <math.h>
#include <time.h>
#include <float.h>
#define VRAI 1
#define FAUX 0

typedef char BOOLEEN;

// mexFunction used as an entry point
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) {
    
    Engine *ep;
    
    if (!(ep = engOpen(NULL))) {
        exit(-1);
    }
    
    // rest of the script
    
}

It should be have been written with 'main' or 'WinMain' for an engine application like this. See for example the MATLAB example file:

copyfile(fullfile(matlabroot,'extern','examples','eng_mat','engwindemo.c'),'.','f')

which uses 'WinMain' as the entry point.