\(\text{FileSeek}\)¶
You can use the \(\text{FileSeek}\) function to position a file pointer in a file.
You can use the \fileseek
backslash command to insert this function.
The following variants of this function are available:
\(\text{boolean } \text{FileSeek} \left ( \text{<file number>}, \text{<offset>} \right )\)
The \(\text{<file number>}\) parameter is an integer value returned by one of the \(\text{FileOpen}\ldots\) functions. The \(\text{<offset>}\) parameter indicates the byte offset into the file where you want the file pointer to be placed. The file offset is zero based rather than one based.
The \(\text{FileSeek}\) function returns true
on success or false
on error.
After using the \(\text{FileSeek}\) function, you will generally want to call one of the \(\text{FileRead}\ldots\) or \(\text{FileWrite}\ldots\) functions to read or update the file contents.
The Figure 137 shows how you can use the \(\text{FileOpenWrite}\) function.
Note
The \(\text{FileRead}\ldots\) and \(\text{FileWrite}\ldots\) functions will advance the file pointer so you do not need to use the \(\text{FileSeek}\) function to read or write sequentially through a file.
Note
The \(\text{FileOpenRead}\) and \(\text{FileOpenWriteTruncate}\) functions will automatically position the file pointer to offset 0. The \(\text{FileOpenWrite}\) function will place the file pointer at the end of the file.