Reading and writing text or binary files
You use PowerScript text file functions to read and write
ASCII text in line mode or stream mode, or to read and write binary
files in stream mode:
- In line
mode
, you can read a file a line at a time until either
a carriage return or line feed (CR/LF) or the end-of-file
(EOF) is encountered. When writing to the file after the specified
string is written, PowerScript appends a CR/LF. - In stream mode
, you can read
the entire contents of the file, including any CR/LFs.
When writing to the file, you must write out the specified string (but
not append a CR/LF).
Reading a file into a MultiLineEdit You can use stream mode to read an entire file into a MultiLineEdit,
and then write it out after it has been modified.
Understanding the position pointer
When PowerBuilder opens a file, it assigns the file a unique
integer and sets the position pointer for the file to the position
you specify (the beginning or end of the file). You use the integer
to identify the file when you want to read the file, write to it,
or close it. The position pointer defines where the next read or
write will begin. PowerBuilder advances the pointer automatically
after each read or write.
You can also set the position pointer with the FileSeek function.
File functions
These are the built-in PowerScript functions that manipulate
files:
| Function | Data type returned | Action |
|---|---|---|
| FileClose | Integer | Closes the specified file |
| FileDelete | Boolean | Deletes the specified file |
| FileExists | Boolean | Determines whether the specified file exists |
| FileLength | Long | Obtains the length of the specified file |
| FileOpen | Integer | Opens the specified file |
| FileRead | Integer | Reads from the specified file |
| FileSeek | Long | Seeks to a position in the specified file |
| FileWrite | Integer | Writes to the specified file |
For information about using these functions in PowerBuilder
for Unicode, see “Reading and writing files”.