The difference between cin.ignore and cin.sync

c++, iostream

Solution

`cin.ignore` discards characters, up to the number specified, or until the delimiter is reached (if included). If you call it with no arguments, it discards one character from the input buffer.

For example, `cin.ignore (80, '\n')` would ignore either 80 characters, or as many as it finds until it hits a newline.

`cin.sync` discards all unread characters from the input buffer. However, it is not guaranteed to do so in each implementation. Therefore, `ignore` is a better choice if you want consistency.

`cin.sync()` would just clear out what's left. The only use I can think of for `sync()` that can't be done with `ignore` is a replacement for `system ("PAUSE");`:

cin.sync(); //discard unread characters (0 if none)
cin.get(); //wait for input

With `cin.ignore()` and `cin.get()`, this could be a bit of a mixture:

cin.ignore (std::numeric_limits<std::streamsize>::max(),'\n'); //wait for newline
//cin.get()

If there was a newline left over, just putting `ignore` will seem to skip it. However, putting both will wait for two inputs if there is no newline. Discarding anything that's not read solves that problem, but again, isn't consistent.

Problem

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