c++ - Finding current executable's path without /proc/self/exe
It seems to me that Linux has it easy with /proc/self/exe. But I'd like to know if there is a convenient way to find the current application's directory in C/C++ with cross-platform interfaces. I've seen some projects mucking around with argv[0], but it doesn't seem entirely reliable. 

Some OS-specific interfaces:

Mac OS X: _NSGetExecutablePath() (man 3 dyld)
Linux: readlink /proc/self/exe
Solaris: getexecname()
FreeBSD: sysctl CTL_KERN KERN_PROC KERN_PROC_PATHNAME -1
FreeBSD if it has procfs: readlink /proc/curproc/file (FreeBSD doesn't have procfs by default)
NetBSD: readlink /proc/curproc/exe
DragonFly BSD: readlink /proc/curproc/file 
Windows: GetModuleFileName() with hModule = NULL

There are also third party libraries that can be used to get this information, such as whereami as mentioned in prideout's answer, or if you are using Qt,  QCoreApplication::applicationFilePath() as mentioned in the comments.
The portable (but less reliable) method is to use argv[0].  Although it could be set to anything by the calling program, by convention it is set to either a path name of the executable or a name that was found using $PATH.
Some shells, including bash and ksh, set the environment variable "_" to the full path of the executable before it is executed.  In that case you can use getenv("_") to get it.  However this is unreliable because not all shells do this, and it could be set to anything or be left over from a parent process which did not change it before executing your program.
