To perform I/O operations on a new or existing file, an application must first establish a connection by calling the mmioOpen function. This returns a file handle, which identifies the open file when calling other file I/O functions. Specify the pmmioinfo parameter to identify a pointer to a caller-provided MMIOINFO block containing extra parameters used by mmioOpen. pmmioinfo may be NULL if the default values of the fields of pmmioinfo are sufficient. By specifying an MMIOINFO structure, you can open a memory file, specify a file format I/O procedure, supply a buffer, or specify data transfers in a standard presentation format. For basic file I/O services, set pmmioinfo to NULL. For example, the following code sample shows how to open a data file without a buffer.
hmmio = mmioOpen("filename.ext", NULL, 0);
Basic options for mmioOpen are shown in the following table.
旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿑lag 쿏escription � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_ALLOCBUF 쿞ystem allocates an internal � � 쿔/O buffer. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_APPEND 쿌llows appending to the end of� � 쿪 file. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_BUFSHARED 쿢ses shared memory if MMIO � � 쿪llocates an I/O buffer. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_CREATE 쿎reates a new file. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_DELETE 쿏eletes the file if it already� � 쿮xists. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_NOIDENTIFY 쿏oes not attempt to identify � � 퀃he file type. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_READ 쿚pens a file for reading only � � �(default). � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_READWRITE 쿚pens a file for both reading � � 쿪nd writing. � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_VERTBAR 쿢ses the vertical bar � � 쿬haracter (|) as a file � � 퀂eparator character rather � � 퀃han the plus sign (+). � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_WRITE 쿚pens a file for writing only.� 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�
The following example creates a new file named NEW.TXT and opens it for writing:
hmmio = mmioOpen("NEW.TXT", NULL, MMIO_CREATE | MMIO_WRITE);
You can also use mmioOpen to specify sharing options for data files. These options enable DOS files to be opened and accessed by more than one process, allowing an application to take advantage of the multi-processing feature of the OS/2 operating system.
Sharing options for data files are shown in the following table.
旼컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿑lag 쿏escription � 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_DENYNONE 쿚pens a file without denying other processes � � 퀁ead or write access to the file. � 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_DENYREAD 쿚pens a file and denies other processes read � � 쿪ccess to the file. � 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_DENYWRITE 쿚pens a file and denies other processes write� � 쿪ccess to the file. � 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘MIO_EXCLUSIVE 쿚pens a file with exclusive mode, denying � � 쿽ther processes both read and write access to� � 퀃he file. � 읕컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�