c-file to mex-file pnet.c in OS 10.9.5 MATLAB 2012a

Walter Roberson on 7 Jan 2016

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https://de.mathworks.com/matlabcentral/answers/262925-c-file-to-mex-file-pnet-c-in-os-10-9-5-matlab-2012a#answer_205359

The message is fairly clear: you need to install gcc 4.2 to use that configuration. If it already is installed then you need to create a symbolic link from "gcc-4.2" to the actual software.

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florian schertenleib on 7 Jan 2016

Thanks for your answer, finally I made it! I installed a newer version of xcode (5.0) and run mex -setup again. besides that, i still get warnings. should i care ?

                                 pnet.c:857:2: warning: add explicitbraces to avoid dangling else [-Wdangling-else]
                                
                                 else
                                
                                 ^
                                
                                 pnet.c:
                                
                                 879:55: warning: passing'int *'toparameter of type 'socklen_t *'
                                
                                 (aka'unsigned int *') convertsbetween pointers to integer types with different sign
                                
                                 [-Wpointer-sign]
                                
                                 readlen,MSG_NOSIGNAL,(struct sockaddr *)&my_addr, &fromlen);
                                
                                 ^~~~~~~~
                                
                                 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk//usr/include/sys/socket.h:622:25: note:
                                
                                 passingargument to parameter here
                                
                                 socklen_t *__restrict)__DARWIN_ALIAS_C(recvfrom);
                                
                                 ^
                                
                                 pnet.c:990:83: warning: passing'int *'toparameter of type 'socklen_t *'
                                
                                 (aka'unsigned int *') convertsbetween pointers to integer types with different sign
                                
                                 [-Wpointer-sign]
                                
                                 ...= accept(sock_fd, (struct sockaddr *)&con[con_index].remote_addr,&sin_size)) > -1)
                                
                                 ^~~~~~~~~
                                
                                 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk//usr/include/sys/socket.h:610:69: note:
                                
                                 passingargument to parameter here
                                
                                 intaccept(int, struct sockaddr * __restrict, socklen_t * __restrict)
                                
                                 ^
                                
                                 3 warningsgenerated.

Walter Roberson on 7 Jan 2016

The second and third warnings are applicable to cases where you might have more than 2^31-1 bytes (2 gigabyte) being transferred. If you were working with something that was intended to need to be secure then I would say you need to fix them, but if you are just using the code for your own purposes with no distribution then do not bother.

The warning about the dangling else might indicate a bug in the code. The difficulty is that if you have

                                 if(condition1)
                                
                                 if(condition2)
                                
                                 ...
                                
                                 else
                                
                                 ...

then it is not immediately clear in C whether the "else" belongs to the first "if" or to the second "if". C does have rules to resolve it, but it is something that programmers get confused about, so the compiler warns you in case you did not notice that it was happening. It is better to avoid the problem by putting in explicit blocks, either

                                 if(condition1) {
                                
                                 if(condition2)
                                
                                 ...
                                
                                 else
                                
                                 ...
                                
                                 }

                                 if(condition1) {
                                
                                 if(condition2)
                                
                                 ...
                                
                                 }else
                                
                                 ...