CODEWITHSUNDEEP
c++visual-studiogcc
cristian
cristian

Reputation: 526

which is a good practice to use access function

I have the following code that I want to work also on Linux with GCC 4.8

This is working with VS 2013

if ( _access( trigger->c_str(), 0 ) != -1 ) 
{
   ...
}

I know that on Linux I can use function: access from "unistd.h"

Is there a way to avoid having something like the following ( a more elegant solution ) ?

#ifdef __linux__ 
    #include <unistd.h>
#endif

#ifdef __linux__ 
     if ( access( trigger->c_str(), 0 ) != -1 ) 
     {
          ...
     }
#else
     if ( _access( trigger->c_str(), 0 ) != -1 )
     {
          ...
     }
#endif

Upvotes: 5

Views: 6228

Answers (2)

eerorika
eerorika

Reputation: 238351

A solution that has no duplication, nor relies on a macro definition (besides the predefined one for platform detection) but has slightly more boilerplate than Aracthor's solution:

#ifdef _WIN32 
    inline int access(const char *pathname, int mode) {
        return _access(pathname, mode);
    }
#else
#include <unistd.h>
#endif

I prefer to detect windows, and use posix as fall back, because windows tends to be the exception more often than linux.

Another clean solution would be to define _CRT_NONSTDC_NO_WARNINGS and keep using the POSIX standard access in windows, without warnings about deprecation. As a bonus, this also disables warnings for using the standard strcpy instead of strcpy_s and similar. The latter is also standard (in C11), but optional and hardly any other C library implements them (and also, not all of the _s family functions in msvc comply to C11).

Upvotes: 8

Aracthor
Aracthor

Reputation: 5907

There is another way, header-only solution.

#ifdef __linux__ 
    #include <unistd.h>
#else
    #define access _access
#endif

if ( access( trigger->c_str(), 0 ) != -1 ) 
{
      ...
}

It would include the right file on Linux systems and replace access with _access on other systems.

Upvotes: 3

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