KwickClips Python · 45 sec · free
Why did my old lines vanish?
Short answer. You opened the file with mode w, which erases it first.
Which mode adds without erasing?
Mode a.
Six file modes
| Mode | Does | If missing |
|---|---|---|
| r | reads | error |
| w | erases, writes | creates it |
| a | adds at end | creates it |
| r+ w+ a+ | read + write | like r, w, a |
Remember
| w erases old text |
| a keeps it and adds |
You opened a file to add a line, and old lines vanished. Why? You used the mode w. Mode r only reads. Mode w erases first. Mode a adds at the end. A plus adds reading and writing. Mode w erases old text. Mode a keeps it and adds.
This clip is from the full lesson: Text File Handling: Open, Read, Write and Append — 9 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 12 Computer Science (083), CBSE Class 12 Computer Science (083), CBSE Class 12 Computer Science (083), Cambridge IGCSE Grade 9 Computer Science (0478)
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