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C Low level Disk IO
The Low level file IO is nothing but, the data is read or write to the file directly without the need of buffer. The Low level file IO functions use handles, so the data transfer speed is faster than high level IO functions. The following low level IO functions are defined in io.h header file.
Low level IO Functions
open() Function
The open() function is used to open a file. There are several modes to open a file.
Syntax - open()
Syntax
open(filename, mode);
| Open modes | Meaning |
|---|---|
| O_CREATE | opens a new file for writing |
| O_WRONLY | open a file in write only mode |
| O_RDONLY | open a file in read only mode |
| O_RDWR | opens a file to read and write |
| O_APPEND | open a file for appending |
| O_BINARY | opens a file in a binary mode |
| O_TEXT | used to create a text file |
| O_TRUNC | opens a file for truncates a file |
write() Function
The write() function is used to write data into a file.
Syntax - write()
Syntax
write(int handle, void *buf, unsigned nbytes);
where, buf is the data area, nbytes referred as number of bytes to write into a file.
read() Function
The read() function is used to read from a file.
Syntax - read()
Syntax
read(int handle, void *buf, unsigned nbytes);
close() Function
Syntax - close()
Syntax
close(int handle);
Related to Low Level Disk IO
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