Multitech MultiConnect MTPCIE-EV3, Developer'S Manual

Page: 59 / 63

USING LINUX WITH EV3 DEVICES
MultiConnect
®
PCIe MTPCIE-EV3 Developer Guide 59
Parameters:
fildes – file descriptor
buf – destination buffer pointer
nbyte – number of bytes that write() attempts to write
Returns :
The number of bytes actually written if the operation is completed successfully, otherwise it is -1.
Example
Write strlen(value_to_be_written) bytes from the buffer pointed by
value_to_be_written to the file
associated with the open file descriptor, fd .
char value_to_be_written[] = “dummy_write”;
if (write(fd, value_to_be_written, strlen(value_to_be_written)) < 0)
{
/* Error Management Routine */
} else {
/* Value Written */
}
close()
The close() function shall deallocate the file descriptor indicated by fildes . To deallocate means to make the file
descriptor available for return by subsequent calls to open() or other functions that allocate file descriptors.
Header File
unistd.h
Prototype:
int close(int fildes);
Parameters:
fildes - file descriptor
Returns :
0 if successful, otherwise it is -1.
Example
Close the ttyUSBx file.
if(close(fd) < 0)
{
/* Error Management Routine */
} else {
/* File Closed */
}