_dos_write

Writes to a file.

Defined in header <dos.h>

Syntax

#include <dos.h>
unsigned  _dos_write(int handle, void far *buf,
                     unsigned  len, unsigned *nwritten);

Portability

Remarks

_dos_write uses DOS function 0x40 to write len bytes from the buffer pointed to by the far pointer huf to the file associated with handle.

_dos_write does not translate a linefeed character (LF) to a CR/LF pair because all its files are binary files.

The actual number of bytes written is stored at the location pointed to by nwritten. If the number of bytes actually written is less than that requested, the condition should be considered an error and probably indicates a full disk.

For disk files, writing always proceeds from the current file pointer. On devices, bytes are directly sent to the device.

Return value

On successful completion, _dos_read returns 0. Otherwise, it returns the DOS error code and the global variable errno is set to one of the following:

EACCES Permission denied

See also

• _dos_open
• _dos_creat
• _dos_read

Example

#include <dos.h>
#include <string.h>
#include <stdio.h>

int* main(void)
{
   unsigned count;
   int handle;
   char buf[ll] =  "0123456789";
   /* create a file containing  10 bytes */
   if (_dos_creat("DUMMY.FIL",  _A_NORMAL, &handle) != 0) {
      perror("Unable to create  DUMMY.FIL");
      return 1;
    }
   if {_dos_write (handle, buf, strlen(buf), &count) != 0) {
      perror ("Unable to write to DUMMY.FIL");
      return 1;
   }
   _dos_close (handle);   /* close the file */
   return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

• Microsoft C runtime (search)

These are search links, not yet checked by hand.

Extraction notes

• heading `dos write` read as `_dos_write`

Stable link: /3.1/dos.h/_dos_write/ · short form /3.1/_dos_write/