# Struggling with ccall

**URL:** <https://discourse.julialang.org/t/struggling-with-ccall/28427>\
**Category:** General Usage\
**Created:** [September 5, 2019, 12:54pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427 "2019-09-05T12:54:45Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 12:54pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/1 "2019-09-05T12:54:45Z")

</div>

Dear Julia developers,  
It’s almost a week I’m trying to call a custom C (or C++) function in Julia.  
In particular what I want is to call a C function I wrote which takes some matrices as arguments and modify one of these. I still didn’t understand if I need to return it or since I give it a pointer it should modify it. Btw, I’m not able to do this task and I’ve tried everything. Your help is REALLY appreciated.

In detail, the function I wrote in C is:  
ccode.c

```julia
#include <math.h>
#include <string.h>
 //#include <stdio.h>
void prob( double **p, double** a, double **b, int na, int nb) {
    for (int i=0; i<na; i++){
        double pr=a[i][0];
        for (int n=0; n<nb; n++){
            double pr_n=pr;
            for (size_t l=0; l < sizeof(b[n]); l++){
                pr_n=pr_n+b[n][l]*a[i][l+1];
            };
            pr_n=1/(1+exp(-pr_n));
            p[i][n]=pr_n;
        };
    };
};

```

then I run with no errors:  
`>g++ -o ccode.so -lm ccode.c -fPIC -shared -Wall`

in my working directory and in Julia I wrote:

ccode.jl

```julia
p=zeros(Float64,1000,3000)
a=rand(Float64,100,1000)
b=rand(Float64,3000,100)

Base.cconvert(::Type{Ptr{Ptr{Cdouble}}},matrix::Matrix{Float64})=Ref{Ptr{Cdouble}}([Ref(matrix,i) for i=1:size(matrix,1):length(matrix)])

function tryccall(p,a,b,nItems,nStud)
#here some tries to convert the matrix in 2d array of pointers:
#p = [Ref(p,i) for i=1:size(p,1):length(p)]
#a = [Ref(a,i) for i=1:size(a,1):length(a)]
#b = [Ref(b,i) for i=1:size(b,1):length(b)]
#p=pointer(p)
#a=pointer(a)
#b=pointer(b)
#p=Base.cconvert(Ptr{Ptr{Cdouble}},p)
#b=Base.cconvert(Ptr{Ptr{Cdouble}},b)
#a=Base.cconvert(Ptr{Ptr{Cdouble}},a)

ccall(("prob", "$pwd()//ccode"), Cvoid, (Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Cint, Cint), p, a, b, 1000,3000)
#eval(:(ccall((:prob, "$pwd()//ccode"), Cvoid, (Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Cint, Cint), p, pars, latents, 1000,3000)))
end

```

But I cannot load the library ccode.so. I also tried to add it with Libdl.opendl but it still doesn’t work.  
Also adding the working directory to the LOAD\_PATH path doesn’t work.

also I get the following error:  
`TypeError: in ccall: first argument not a pointer or valid constant expression, expected Ptr, got Tuple{String,String}`

I tried to use a symbol but it’s still the same.  
What can I do?

Thank you in advance  
Giada

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 1:08pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/2 "2019-09-05T13:08:29Z")

</div>

I first open the dynamic library:

```julia
_H2LIB = dlopen(joinpath(_H2LIBDIR, "libh2") * _H2LIBNUMBERS * ".so")

```

and then I create a library function as

```julia
function new_hmatrix(rows::T, cols::T) where {T}
    # new_amatrix (uint rows, uint cols)
    return PHmatrix(ccall(dlsym(H2Libjl._H2LIB, :new_hmatrix), 
        _phmatrix, 
        (Cuint, Cuint), 
        rows, cols))
end 

```

so that as you can see I use `dlsym` (the C library `H2Libjl._H2LIB` contains a function called `new_hmatrix`).

Would that solve your problem?

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 1:28pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/3 "2019-09-05T13:28:39Z")

</div>

> [@PetrKryslUCSD](#):
>
> ```julia
> _H2LIB = dlopen(joinpath(_H2LIBDIR, "libh2") * _H2LIBNUMBERS * ".so")
> 
> ```

Unfortunately not, when I try to use the `dlopen("workingdir/ccode.so")` function it says:

```julia
ERROR: could not load library "workingdir/ccode.so"
The specified module could not be found.

```

I tried also with “\\” in the path using joinpath but still doesn’t work.

---

<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [September 5, 2019, 2:09pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/4 "2019-09-05T14:09:38Z")

</div>

A few things:

- You want to compile this as a c-library so use `gcc` instead of `g++`.
- Second, the path name needs to be a constant so pull it out as `const lib = "..."`
- Thirdly, this is probably not what you want.

```julia
julia> "$pwd()//ccode"
"pwd()//ccode"

```

There are some more issues but that should at least get you to start segfaulting 🙂

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 2:41pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/5 "2019-09-05T14:41:25Z")

</div>

1. thanks, I changed it to gcc.
2. I tried both `const lib="fullpathtoworkingdir//ccode.so"` and `const lib="ccode.so"`, also without “.so”.
3. You are right again, but it doesn’t work anyway with any of the possible paths!

I restarted Julia and tried to push the working directory path in the Libdl.DL\_LOAD\_PATH, if I do

```julia
const lib="ccode.so"
dlopen(lib)

```

now I have

```julia
could not load library "ccode"
The operation completed successfully.

```

instead of

```julia
could not load library "ccode"
The specified module could not be found.

```

So, I don’t think I’ve done anything useful ☹

---

<div class="post-metadata">

**Author:** ![cchderrick](https://avatars.discourse-cdn.com/v4/letter/c/ecd19e/32.png) [@cchderrick](https://discourse.julialang.org/u/cchderrick)\
**Post date:** [September 5, 2019, 3:46pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/6 "2019-09-05T15:46:18Z")

</div>

```julia
# The setup
import Libdl
Libdl

const ccode_lib = joinpath(@ __DIR__ ,"ccode.so")
Libdl.dlopen(ccode_lib)

# The code
p = zeros(Float64,1000,3000)
a = rand(Float64,100,1000)
b = rand(Float64,3000,100)

Base.cconvert(::Type{Ptr{Ptr{Cdouble}}},matrix::Matrix{Float64})=Ref{Ptr{Cdouble}}([Ref(matrix,i) for i=1:size(matrix,1):length(matrix)])

ccall(
    ("prob", ccode_lib),
    Cvoid,
    (Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Cint, Cint),
    p, a, b, 1000,3000
)

```

This should at least get you to

> signal (11): Segmentation fault

Looks like it has to be absolute path and `const` for `dlopen` and `ccall`?

The folder looks like:

```julia
|-ccode.c
|-ccode.jl
|-ccode.so

```

and I used this to build the so:

> `gcc -o ccode.so -lm ccode.c -fPIC -shared -Wall`

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 4:01pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/7 "2019-09-05T16:01:25Z")

</div>

> [@cchderrick](#):
>
> const ccode\_lib = joinpath(@ **DIR** ,“ccode.so”) Libdl.dlopen(ccode\_lib)

Nope,  
still the same errors.

Just to be more precise: I’m using Julia 1.2 on a Windows 10 computer.

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 4:03pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/8 "2019-09-05T16:03:22Z")

</div>

So how are you compiling? In mingw?

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 4:06pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/9 "2019-09-05T16:06:22Z")

</div>

Yes, MinGW latest release.

---

<div class="post-metadata">

**Author:** ![cchderrick](https://avatars.discourse-cdn.com/v4/letter/c/ecd19e/32.png) [@cchderrick](https://discourse.julialang.org/u/cchderrick)\
**Post date:** [September 5, 2019, 5:22pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/10 "2019-09-05T17:22:38Z")

</div>

Well, I can’t reproduce the problem.

Here is my “latest” MinGW gcc

> gcc.exe (x86\_64-posix-seh-rev0, Built by MinGW-W64 project) 8.1.0

Compile with this:

> /c/Program\ Files/mingw-w64/x86\_64-8.1.0-posix-seh-rt\_v6-rev0/mingw64/bin/gcc -o ccode.so -lm ccode.c -fPIC -shared -Wall

Also Julia v1.2.0 on Windows 10. I have no error.

```julia
julia> const ccode_lib = joinpath(@ __DIR__ ,"ccode.so")
"C:\\Work\\Julia-Repo\\ccall_example\\ccode.so"

julia> Libdl.dlopen(ccode_lib)
Ptr{Nothing} @0x0000000067e80000

julia> p = zeros(Float64,2,3)
2×3 Array{Float64,2}:
 0.0 0.0 0.0
 0.0 0.0 0.0
julia> a = rand(Float64,100,2)
100×2 Array{Float64,2}:
 0.123991 0.405554
 0.895298 0.652647
 ⋮
 0.0702061 0.685377
 0.567912 0.451844

julia> b = rand(Float64,3,100)
3×100 Array{Float64,2}:
 0.0509991 0.0508403 0.887033 0.384972 0.00537979 … 0.784158 0.0625842 0.91498 0.0987885 0.6987
 0.891435 0.65253 0.568233 0.537573 0.431059 0.13089 0.297716 0.495508 0.654329 0.730187
 0.0243292 0.427209 0.904488 0.265174 0.538062 0.130987 0.650718 0.370341 0.916315 0.826939

julia> Base.cconvert(::Type{Ptr{Ptr{Cdouble}}},matrix::Matrix{Float64})=Ref{Ptr{Cdouble}}([Ref(matrix,i) for i=1:size(matrix,1):length(matrix)])

julia> ccall(
           ("prob", ccode_lib),
               Cvoid,
                   (Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Ptr{Ptr{Cdouble}}, Cint, Cint),
                       p, a, b, 2,3
                       )
julia> p
2×3 Array{Float64,2}:
 0.906484 0.880958 0.893602
 0.911566 0.866668 0.0

```

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 5:31pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/11 "2019-09-05T17:31:57Z")

</div>

Sorry, what do you mean for:

```julia
Compile with this:

/c/Program\ Files/mingw-w64/x86_64-8.1.0-posix-seh-rt_v6-rev0/mingw64/bin/gcc -o ccode.so -lm ccode.c -fPIC -shared -Wall

```

?

it means I have to run it in the folder in which I have “ccode.c”, right?

Anyway I don’t know what’s wrong, my gcc version is `gcc (MinGW.org GCC-8.2.0-3) 8.2.0`

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 5:46pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/12 "2019-09-05T17:46:05Z")

</div>

What does `nm ccode.so` say? Can you see the symbol (`prob`) that you expect?

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 5:50pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/13 "2019-09-05T17:50:15Z")

</div>

The file ccode.so it’s not readable (at least I don’t know how to to do it) 😅

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 5:54pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/14 "2019-09-05T17:54:33Z")

</div>

Use the `nm` program.

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 5:56pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/15 "2019-09-05T17:56:17Z")

</div>

> [@cchderrick](#):
>
> gcc -o ccode.so -lm ccode.c -fPIC -shared -Wall

This is the result

````julia
68085060 b .bss
68085024 b .bss
68085008 b .bss
68085060 b .bss
68085000 b .bss
68085034 b .bss
68085020 b .bss
68085054 b .bss
68085020 b .bss
68088010 d .CRT$XDA
68088014 d .CRT$XDZ
68088000 d .CRT$XLA
68081b74 t .ctors.65535
68082008 d .data
68082000 d .data
68082004 d .data
68082008 d .data
68082004 d .data
6808e000 N .debug_abbrev
6808b000 N .debug_aranges
6808c000 N .debug_info
6808f000 N .debug_line
680840c8 r .eh_frame
68084494 r .eh_frame
6808412c r .eh_frame
68087070 i .idata$4
6808703c i .idata$4
680870b8 i .idata$5
680870b4 i .idata$5
680870d4 i .idata$5
680870d8 i .idata$5
680870e0 i .idata$5
680870b0 i .idata$5
680870ac i .idata$5
680870a8 i .idata$5
680870c4 i .idata$5
680870e4 i .idata$5
680870e8 i .idata$5
680870ec i .idata$5
680870f0 i .idata$5
680870f4 i .idata$5
680870f8 i .idata$5
680870a4 i .idata$5
680870fc i .idata$5
680870c0 i .idata$5
680870a0 i .idata$5
680870cc i .idata$5
680870a0 i .idata$5
680870bc i .idata$5
680870d4 i .idata$5
680870c8 i .idata$5
68087194 i .idata$6
680871ac i .idata$6
680871bc i .idata$6
68087166 i .idata$6
680871ca i .idata$6
6808724a i .idata$6
68087152 i .idata$6
68087240 i .idata$6
680871dc i .idata$6
68087236 i .idata$6
68087142 i .idata$6
6808722e i .idata$6
68087104 i .idata$6
68087224 i .idata$6
6808711c i .idata$6
6808721e i .idata$6
680871ec i .idata$6
68087214 i .idata$6
680871fa i .idata$6
6808720c i .idata$6
68087204 i .idata$6
68087134 i .idata$6
68087178 i .idata$6
68083048 r .rdata
68083000 r .rdata
6808311c r .rdata$zzz
680831cc r .rdata$zzz
68083108 r .rdata$zzz
680831e0 r .rdata$zzz
68081540 t .text
68081000 t .text
68081b60 t .text
68081790 t .text
68081380 t .text
68081390 t .text
68081290 t .text
68081ab0 t .text
680811b0 t .text
68081440 t .text
68081b60 t .text.startup
68089000 d .tls$AAA
6808901c d .tls$ZZZ
00000000 A .weak. ___deregister_frame_info.___ EH_FRAME_BEGIN__
00000000 A .weak. ___register_frame_info.___ EH_FRAME_BEGIN__
680815a0 T ____ w64_mingwthr_add_key_dtor
68081630 T ____ w64_mingwthr_remove_key_dtor
68088000 D ___crt_xc_end__
68088000 D ___crt_xc_start__
68088000 D ___crt_xi_end__
68088000 D ___crt_xi_start__
68088000 D ___crt_xl_start__
68088010 D ___crt_xp_end__
68088010 D ___crt_xp_start__
68088010 D ___crt_xt_end__
68088010 D ___crt_xt_start__
68081b70 T ___CTOR_LIST__
         w ___deregister_frame_info
68081af8 T ___dllonexit
680813d0 T ___do_global_ctors
68081390 T ___do_global_dtors
68081b7c T ___DTOR_LIST__
68081490 T ___dyn_tls_init@12
68083044 R ___dyn_tls_init_callback
680840c8 R ___EH_FRAME_BEGIN__
68084494 r ___FRAME_END__
68081260 T ___gcc_deregister_frame
680811b0 T ___gcc_register_frame
68080000 A ___ImageBase
68081420 T ___main
680816d0 T ___mingw_TLScallback
         w ___register_frame_info
680831f4 R ___RUNTIME_PSEUDO_RELOC_LIST__
680831f4 R ___RUNTIME_PSEUDO_RELOC_LIST_END__
68081530 T ___tlregdtor
68089020 D ___tls_end__
68089000 D ___tls_start__
68088000 D ___xl_a
68088004 D ___xl_c
68088008 D ___xl_d
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68085064 B __bss_end__
68085000 B __bss_start__
6808505c B __CRT_MT
68081b70 T __CTOR_LIST__
68082008 D __data_end__
68082000 D __data_start__
00000000 A __dll__
00000000 A __dll_characteristics__
68081b7c T __DTOR_LIST__
         U __end__
68081af0 T __errno
00000200 A __file_alignment__
68087000 I __head_libkernel32_a
68087014 I __head_libmsvcrt_a
68087104 I __IAT_end__
680870a0 I __IAT_start__
68080000 A __image_base__
680870d4 I __imp____ dllonexit
680870d8 I __imp___ errno
680870dc I __imp___ iob
680870e0 I __imp__ abort
680870e4 I __imp__ calloc
680870a0 I __imp__ DeleteCriticalSection@4
680870a4 I __imp__ EnterCriticalSection@4
680870e8 I __imp__ exp
680870ec I __imp__ fflush
680870f0 I __imp__ free
680870a8 I __imp__ FreeLibrary@4
680870f4 I __imp__ fwrite
680870ac I __imp__ GetLastError@0
680870b0 I __imp__ GetModuleHandleA@4
680870b4 I __imp__ GetProcAddress@8
680870b8 I __imp__ InitializeCriticalSection@4
680870bc I __imp__ LeaveCriticalSection@4
680870c0 I __imp__ LoadLibraryA@4
680870f8 I __imp__ malloc
680870c4 I __imp__ TlsGetValue@4
680870fc I __imp__ vfprintf
680870c8 I __imp__ VirtualProtect@16
680870cc I __imp__ VirtualQuery@12
68087288 I __libkernel32_a_iname
680872c4 I __libmsvcrt_a_iname
00000000 A __loader_flags__
00000001 A __major_image_version__
00000004 A __major_os_version__
00000004 A __major_subsystem_version__
00000000 A __minor_image_version__
00000000 A __minor_os_version__
00000000 A __minor_subsystem_version__
68081180 T __onexit
680818d0 T __pei386_runtime_relocator
680831f4 R __rt_psrelocs_end
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00001000 A __section_alignment__
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00001000 A __size_of_stack_commit__
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00000003 A __subsystem__
6808901c D __tls_end
68085030 B __tls_index
68089000 D __tls_start
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68081ae0 T _calloc
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68082000 d _deregister_frame_fn
68081380 T _DllMain@12
68081060 T _DllMainCRTStartup@12
68081b50 T _EnterCriticalSection@4
68081ad8 T _exp
68081ad0 T _fflush
68081ac8 T _free
68081b48 T _FreeLibrary@4
68081ac0 T _fwrite
68081b40 T _GetLastError@0
68081b38 T _GetModuleHandleA@4
68081b30 T _GetProcAddress@8
68085060 B _hmod_libgcc
68081b28 T _InitializeCriticalSection@4
68081b20 T _LeaveCriticalSection@4
68081b18 T _LoadLibraryA@4
68081ab8 T _malloc
6808502c B _mingw_initltsdrot_force
68085028 B _mingw_initltsdyn_force
68085024 B _mingw_initltssuo_force
68085008 b _obj
68081290 T _prob
68081b60 t _register_frame_ctor
68081b10 T _TlsGetValue@4
68081ab0 T _vfprintf
68081b08 T _VirtualProtect@16
68081b00 T _VirtualQuery@12```
````

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 6:18pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/16 "2019-09-05T18:18:56Z")

</div>

```julia
68081290 T _prob

```

Now you know you have an actual dyn library with your function in it. Have you tried

```julia
const ccode_lib = joinpath(@ __DIR__ ,"ccode.so")
Libdl.dlopen(ccode_lib)

```

?

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 6:39pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/17 "2019-09-05T18:39:22Z")

</div>

> [@PetrKryslUCSD](#):
>
> const ccode\_lib = joinpath(@ **DIR** ,“ccode.so”) Libdl.dlopen(ccode\_lib)

Yes,

```julia
ERROR: could not load library "C:\Users\wd\ccode.so"
The specified module could not be found.

Stacktrace:
 [1] #dlopen#3(::Bool, ::typeof(dlopen), ::String, ::UInt32) at C:\cygwin\home\Administrator\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.2\Libdl\src\Libdl.jl:109
 [2] dlopen at C:\cygwin\home\Administrator\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.2\Libdl\src\Libdl.jl:109 [inlined] (repeats 2 times)
 [3] top-level scope at REPL[8]:1

```

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 6:57pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/18 "2019-09-05T18:57:43Z")

</div>

What is your Julia version?

---

<div class="post-metadata">

**Author:** ![giadasp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giadasp/32/10143_2.png) [@giadasp](https://discourse.julialang.org/u/giadasp)\
**Post date:** [September 5, 2019, 7:15pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/19 "2019-09-05T19:15:02Z")

</div>

Julia 1.2

---

<div class="post-metadata">

**Author:** ![PetrKryslUCSD](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/petrkryslucsd/32/215825_2.png) [@PetrKryslUCSD](https://discourse.julialang.org/u/PetrKryslUCSD)\
**Post date:** [September 5, 2019, 7:18pm UTC](https://discourse.julialang.org/t/struggling-with-ccall/28427/20 "2019-09-05T19:18:10Z")

</div>

The rest? Do `versioninfo()` please.

[Next page](https://discourse.julialang.org/t/struggling-with-ccall/28427.md?page=2)