| LONG _llseek(hf, lOffset, nOrigin) | |||||
| HFILE hf; | /* file handle | */ | |||
| LONG lOffset; | /* number of bytes to move | */ | |||
| int nOrigin; | /* position to move from | */ | |||
The _llseek function repositions the pointer in a previously opened file.
hf
Identifies the file.
lOffset
Specifies the number of bytes the pointer is to be moved.
nOrigin
Specifies the starting position and direction of the pointer. This parameter must be one of the following values:
| Value | Meaning |
| 0 | Move the file pointer lOffset bytes from the beginning of the file. |
| 1 | Move the file pointer lOffset bytes from its current position. |
| 2 | Move the file pointer lOffset bytes from the end of the file. |
The return value specifies the new offset, in bytes, of the pointer from the beginning of the file, if the function is successful. Otherwise, the return value is HFILE_ERROR.
When a file is initially opened, the file pointer is positioned at the beginning of the file. The _llseek function permits random access to a file's contents by moving the pointer an arbitrary amount without reading data.
The following example uses the _llseek function to move the file pointer to the end of an existing file:
HFILE hfAppendFile;
/* Open the write file. */
hfAppendFile = _lopen("append.txt", WRITE);
/* Move to the end of the file. */
if (_llseek(hfAppendFile, 0L, 2) == -1) {
ErrorHandler();
}