Calllib() call for a C character pointer, doesn't retrieve the whole string

I have the below function in my dll, which is loaded into MATLAB using loadlibrary() -

unsigned int DevId(unsigned int Chapterid,unsigned int SerialNum,CHAR* devid,unsigned int Len);

The corresponding function definition in MATLAB is -

[ulong, int8Ptr] DevId(long, ulong, int8Ptr, ulong)

I am trying to execute this function using calllib(), to retrive the "devid" , using the below matlab code

Cname=libpointer('int8Ptr',0);
CLen = 0;
calllib('<dll>','DevId',SID,CN,Cname,CLen);

When i try for 'Cname.Value', i get the output as "52" (which is the ASCII for 4,the first character of the string i should get) and CLen is still 0.

>> Cname.Value

ans =

    int8

     52

>> Clen

Clen =

       0

Could you please let me know if i am doing something wrong.

String i am expecting as the output is 40-XXXA-XX2

Answer 1

[Alexander Jaiboy]

The solution for the issue is

bufsize = 100;
bufptr = libpointer('int8Ptr',zeros(bufsize,1,'int8'));
calllib('<dll>','DevId',SID,CN,bufptr,bufsize);
app.CardName=char(bufptr.value);
convertCharsToStrings(char(bufptr.value));