KwickClips Cyber Safety and Ethics · 41 sec · free
How do you keep old data?
Short answer. Use ios::app.
How do you join modes?
With |.
File modes
| Mode | Does |
|---|---|
| ios::out | erases, writes |
| ios::app | adds at end |
| ios::in | reads |
| ios::binary | raw bytes |
Remember
| Keep old data: ios::app | |
| Join modes with |
You wrote to a file, and old data vanished. Why? The mode decides what happens to old data. Out erases old data. App adds at the end. In reads. Binary uses raw bytes. To keep old data, use app. Join modes with a vertical bar.
This clip is from the full lesson: File Handling in C++ — 7 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: NIOS Senior Secondary Computer Science (330), Programming All levels C++, Programming All levels C++
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