i followed the solution given here: Passing pointer argument in MATLAB to a C-DLL

Question

0

Editorial Team

Asked: June 14, 20262026-06-14T07:07:48+00:00 2026-06-14T07:07:48+00:00

i followed the solution given here: Passing pointer argument in MATLAB to a C-DLL

0

i followed the solution given here:
Passing pointer argument in MATLAB to a C-DLL function foo(char**)

i add a string received via tcp socket, this is the reduced example

c-dll:

void test(char **u1, char **y1)
{
   std::string recvString("Test Output"); //this string change
   *y1 = (char*) mxRealloc(*y1, recvString.size()+1); //get memory
   *y1 = strdup(recvString.c_str()); //copy
}

matlab:

loadlibrary('rriMonitor.dll', 'rriMonitor.h');

vpu = libpointer('stringPtrPtr',{'test input'});
vpv = libpointer('stringPtrPtr',{''});

calllib('rriMonitor','test',vpu,vpv);
vpv.value{1}    %gives correct string 'Test Output'

%clear vpv; % CRASH also

unloadlibrary 'rriMonitor'

clear vpu; % everything fine
clear vpv; % CRASH

this is working so far. my problem is that a final:

clear vpv  (alias pstr in the example)

crashes matlab ((R2011a) 64-bit)

how to clear the lib.pointer ?

(i tried change java vm, but same behavior)

MATLAB Version  : 7.12.0.635 (R2011a)
Operating System: Microsoft Windows 7
Processor ID    : x86 Family 6 Model 14 Stepping 5, GenuineIntel
Virtual Machine : Java 1.7.0_09-b05 with Oracle Corporation Java HotSpot(TM) 64-Bit    Server VM mixed mode
Window System   : Version 6.1 (Build 7601: Service Pack 1)

Fault Count: 1




Abnormal termination:

Segmentation violation


Register State (from fault):

RAX = 00000000015ccf68  RBX = 000000000e6faab0

RCX = 0000000001e90000  RDX = 0000000000000000

RSP = 00000000015ccef0  RBP = 0000000000000000
RSI = 0000000001e90000  RDI = 000000000e6faac0

R8 = 000000000e6faac0   R9 = 00000000040fa250
R10 = 0000000029c25fa0  R11 = 00000000015cd090
R12 = 000000000422e750  R13 = 0000000000000000
R14 = 0000000000000001  R15 = 000000006156fd40

RIP = 000000007709324e  EFL = 00010246

CS = 0033   FS = 0053   GS = 002b


Stack Trace (from fault):
[  0] 0x000000007709324e                      C:/Windows/SYSTEM32/ntdll.dll+00340558 ( RtlFreeHeap+000078 )
[  1] 0x000000007698300a                   C:/Windows/system32/kernel32.dll+00143370 ( HeapFree+000010 )
[  2] 0x000000006b89cabc C:/Windows/WinSxS/amd64_microsoft.vc90.crt_1fc8b3b9a1e18e3b_9.0.30729.6161_none_08e61857a83bc251/MSVCR90.dll+00314044 ( free+000028 )
[  3] 0x000007fef131f9d9 C:/Program Files/MATLAB/R2011a/bin/win64/libmwcli.dll+00063961 ( RefDataType::AssignPointer+002153 )
[  4] 0x000007fef131cb2d C:/Program Files/MATLAB/R2011a/bin/win64/libmwcli.dll+00052013 ( callstdfcn+005693 )
[  5] 0x000007fef131c7a4 C:/Program Files/MATLAB/R2011a/bin/win64/libmwcli.dll+00051108 ( callstdfcn+004788 )
[  6] 0x000000005f0a0d83   C:/Program Files/MATLAB/R2011a/bin/win64/udd.dll+00200067 ( UDInterface::destroyInternals+000067 )
[  7] 0x000000005f0a0f06   C:/Program Files/MATLAB/R2011a/bin/win64/udd.dll+00200454 ( UDInterface::destroyUnconditional+000230 )
[  8] 0x000000005f0a1034   C:/Program Files/MATLAB/R2011a/bin/win64/udd.dll+00200756 ( UDInterface::copyE+000052 )
[  9] 0x000000005e1f0750 C:/Program Files/MATLAB/R2011a/bin/win64/udd_mi.dll+00264016 ( judiSetDynamicPropertyValue+008368 )
[ 10] 0x0000000075a28723 C:/Program Files/MATLAB/R2011a/bin/win64/libmx.dll+00034595 ( mxSetObjectCreateDestroyFn+000275 )
[ 11] 0x0000000075a288aa C:/Program Files/MATLAB/R2011a/bin/win64/libmx.dll+00034986 ( mxSetObjectCreateDestroyFn+000666 )
[ 12] 0x0000000075a7e8e5 C:/Program Files/MATLAB/R2011a/bin/win64/libmx.dll+00387301 ( mxClearArrayContents+000021 )
[ 13] 0x0000000051672928 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00731432 ( inDestroyWS+465608 )
[ 14] 0x0000000051666932 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00682290 ( inDestroyWS+416466 )
[ 15] 0x00000000516754ee C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00742638 ( inDestroyWS+476814 )
[ 16] 0x0000000051675930 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00743728 ( inDestroyWS+477904 )
[ 17] 0x00000000615201a9 C:/Program Files/MATLAB/R2011a/bin/win64/m_dispatcher.dll+00065961 ( mdLogging::log_function_entry+000201 )
[ 18] 0x0000000061520156 C:/Program Files/MATLAB/R2011a/bin/win64/m_dispatcher.dll+00065878 ( mdLogging::log_function_entry+000118 )
[ 19] 0x000000006151fb98 C:/Program Files/MATLAB/R2011a/bin/win64/m_dispatcher.dll+00064408 ( Mfunction_handle::dispatch+000456 )
[ 20] 0x000000005164182b C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00530475 ( inDestroyWS+264651 )
[ 21] 0x000000005163e082 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00516226 ( inDestroyWS+250402 )
[ 22] 0x0000000051654c73 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00609395 ( inDestroyWS+343571 )
[ 23] 0x0000000051654dc0 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00609728 ( inDestroyWS+343904 )
[ 24] 0x000000005164624b C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00549451 ( inDestroyWS+283627 )
[ 25] 0x00000000516442ac C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00541356 ( inDestroyWS+275532 )
[ 26] 0x0000000051651009 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00593929 ( inDestroyWS+328105 )
[ 27] 0x000000006151f859 C:/Program Files/MATLAB/R2011a/bin/win64/m_dispatcher.dll+00063577 ( Mfh_file::dispatch_fh+000473 )
[ 28] 0x000000006151fccf C:/Program Files/MATLAB/R2011a/bin/win64/m_dispatcher.dll+00064719 ( Mfunction_handle::dispatch+000767 )
[ 29] 0x00000000516c6de8 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01076712 ( inSetPredictor+001000 )
[ 30] 0x00000000516d3415 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01127445 ( inInitInterestRegistry+004309 )
[ 31] 0x00000000516d5175 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01134965 ( inIsCodeBlockComplete+007445 )
[ 32] 0x00000000516d5148 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01134920 ( inIsCodeBlockComplete+007400 )
[ 33] 0x00000000516d510e C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01134862 ( inIsCodeBlockComplete+007342 )
[ 34] 0x0000000051698113 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+00885011 ( inGetSeqVarPtrsFromCurrentWS+007315 )
[ 35] 0x00000000516c98e0 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01087712 ( inEvalCmdWithLocalReturn+000304 )
[ 36] 0x00000000516c983c C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01087548 ( inEvalCmdWithLocalReturn+000140 )
[ 37] 0x00000000516c97f1 C:/Program Files/MATLAB/R2011a/bin/win64/m_interpreter.dll+01087473 ( inEvalCmdWithLocalReturn+000065 )
[ 38] 0x0000000079fb833a C:/Program Files/MATLAB/R2011a/bin/win64/libmwbridge.dll+00033594 ( mnDebugPrompt+000106 )
[ 39] 0x0000000079fbd0d2 C:/Program Files/MATLAB/R2011a/bin/win64/libmwbridge.dll+00053458 ( mnParser+000418 )
[ 40] 0x00000000749ab604   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00243204 ( mcrInstance::mnParser_on_interpreter_thread+000036 )
[ 41] 0x000000007498ed24   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00126244 ( DepfunRules::postWarning+045636 )
[ 42] 0x000000007498edb1   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00126385 ( DepfunRules::postWarning+045777 )
[ 43] 0x0000000001b79676   C:/Program Files/MATLAB/R2011a/bin/win64/uiw.dll+00366198 ( UIW_IsUserMessage+000086 )
[ 44] 0x0000000001b79d44   C:/Program Files/MATLAB/R2011a/bin/win64/uiw.dll+00367940 ( ws_ProcessPendingEventsWaitForWindows+000356 )
[ 45] 0x0000000076f687fe                     C:/Windows/system32/USER32.dll+00165886 ( GetMenuBarInfo+000638 )
[ 46] 0x0000000076f4f5fb                     C:/Windows/system32/USER32.dll+00062971 ( SystemParametersInfoW+000235 )
[ 47] 0x0000000076f54895                     C:/Windows/system32/USER32.dll+00084117 ( IsProcessDPIAware+000465 )
[ 48] 0x0000000077091225                      C:/Windows/SYSTEM32/ntdll.dll+00332325 ( KiUserCallbackDispatcher+000031 )
[ 49] 0x0000000076f59e6a                     C:/Windows/system32/USER32.dll+00106090 ( SfmDxSetSwapChainStats+000026 )
[ 50] 0x0000000076f5615e                     C:/Windows/system32/USER32.dll+00090462 ( GetMessageA+000078 )
[ 51] 0x0000000001b53f07   C:/Program Files/MATLAB/R2011a/bin/win64/uiw.dll+00212743 ( UIW_SetCurrentDialog+000855 )
[ 52] 0x0000000001b7b117   C:/Program Files/MATLAB/R2011a/bin/win64/uiw.dll+00373015 ( ws_FreeSystemFont+000519 )
[ 53] 0x000000005e36b7b3 C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00178099 ( sysq::ws_ppeHook::~ws_ppeHook+009539 )
[ 54] 0x000000005e36cf3c C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00184124 ( svWS_CommitDatabaseUpdates+002796 )
[ 55] 0x000000005e36d97a C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00186746 ( svWS_CommitDatabaseUpdates+005418 )
[ 56] 0x000000005e36dbbd C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00187325 ( svWS_CommitDatabaseUpdates+005997 )
[ 57] 0x000000005e36ddb8 C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00187832 ( svWS_CommitDatabaseUpdates+006504 )
[ 58] 0x000000005e36df10 C:/Program Files/MATLAB/R2011a/bin/win64/libuij.dll+00188176 ( svWS_CommitDatabaseUpdates+006848 )
[ 59] 0x000000007498e28f   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00123535 ( DepfunRules::postWarning+042927 )
[ 60] 0x000000007498f051   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00127057 ( DepfunRules::postWarning+046449 )
[ 61] 0x000000007498f37e   C:/Program Files/MATLAB/R2011a/bin/win64/mcr.dll+00127870 ( DepfunRules::postWarning+047262 )
[ 62] 0x000000013f527304 C:/Program Files/MATLAB/R2011a/bin/win64/MATLAB.exe+00029444 ( ???+000000 )
[ 63] 0x000000013f5273d9 C:/Program Files/MATLAB/R2011a/bin/win64/MATLAB.exe+00029657 ( ???+000000 )
[ 64] 0x000000013f5278cb C:/Program Files/MATLAB/R2011a/bin/win64/MATLAB.exe+00030923 ( ???+000000 )
[ 65] 0x000000007697652d                   C:/Windows/system32/kernel32.dll+00091437 ( BaseThreadInitThunk+000013 )
[ 66] 0x000000007706c521                      C:/Windows/SYSTEM32/ntdll.dll+00181537 ( RtlUserThreadStart+000033 )

Report

Leave an answer
Cancel reply

You must login to add an answer.

Need An Account,

1 Answer

Editorial Team · Answer 1 · 2026-06-14T07:07:49+00:00

SOLVED

dynamicaly allocated memory has to be released in c first!

change c-dll function

void test(char **u1, char **y1)
{
   std::string recvString("Test Output");
   *y1 = strdup(recvString.c_str()); //allocate and copy 
}

add c-dll function

void clear(char** y1)
{
   free(*y1)
   *y1 = NULL;
}

add matlab

loadlibrary('rriMonitor.dll', 'rriMonitor.h');

vpu = libpointer('stringPtrPtr',{'test input'});
vpv = libpointer('stringPtrPtr',{''});

calllib('rriMonitor','test',vpu,vpv);
vpv.value{1}    %gives correct string 'Test Output'

calllib('rriMonitor','clear',vpv);
vpv.value       %null pointer {[]}
clear all       %works

unloadlibrary 'rriMonitor'

Sign Up

Sign In

Forgot Password

The Archive Base Latest Questions

i followed the solution given here: Passing pointer argument in MATLAB to a C-DLL

Leave an answerCancel reply

1 Answer

Leave an answer
Cancel reply