The alloca.h header file consists of

• "_chdir," changes directories
• "_chdrive," changes drives.
• "_fileno," returns the file handle
• "_getcwd," reads the current working directory
• "_getdrive" returns the number of the current drive.
• "GetHandle," gets a device handle
• "_get_osfhandle," gets operating system file handle
• "_heapmin," releases unused heap to the system
• "_isatty," determines if the device is a character device
• "_makepath," creates a path
• "_open_osfhandle," opens a OS file handle
• "_searchenv," searches the environment for a file

If you're porting a UNIX or DOS program, you might also need the functions in other UNIX compatibility headers.

"POSIX Functionality," for information on POSIX naming convetions.