Function 3Eh Close File with Handle

mov bx, Handle ;handle of file or device

mov ah, 3Eh ;Close File with Handle

int 21h

jc error_handler ;carry set means error

Close File with Handle (Function 3Eh) closes a file opened or created with a file-handle function.

Parameter

Handle

Identifies the file to close.

Return Value

If the function is successful, the carry flag is clear. Otherwise, the carry flag is set and the AX register contains an error value, which may be 0006h (ERROR_INVALID_HANDLE).

Comments

When MS-DOS processes this function, any internal buffer for the file is flushed (any pending write operations are completed), any locked regions of the file are unlocked, and the directory is updated to reflect any changes in the file size, date, or time.

Although closing a file invalidates the corresponding handle, MS-DOS may reuse the handle to identify a file that is subsequently opened or created. Programs can use Is File or Device Remote (Function 440Ah) to determine whether a given handle is valid.

See Also

Function 3Ch Create File with Handle
Function 3Dh Open File with Handle
Function 440Ah Is File or Device Remote
Function 5Ah Create Temporary File
Function 5Bh Create New File
Function 6Ch Extended Open/Create