flags

I have a QTreeWidgetItem with two columns of data, is there any way to make only the second column editable? When I do the following: QTreeWidgetItem* item = new QTreeWidgetItem(); item->setFlags(item->flags() | Qt::ItemIsEditable); all columns become editable. Looks like you will have to forgo using QTreeWidget and QTreeWidgetItem and go with QTreeView and QAbstractItemModel . The "Widget" classes are convenience classes that are concrete implementations of the more abstract but more flexible versions. QAbstractItemModel has a call flags(QModelIndex index) where you would return the

What does applying [Flags] really do? I know it modifies the behavior of Enum.ToString , but does it do anything else? (e.g. Different compiler or runtime behavior, etc.) Edit : Yeah, I'm aware that it documents the fact that the enum is intended to be used as bitwise flags, and that it's more logical to apply it to bit flags. I was asking more about concrete behavior changes though, not general programming practices. From an MSDN article : It is interesting to note that when Flags is specified, Parse and Format methods feature advanced capabilities. Likewise, the Parse method can successfully

This question already has an answer here: How to finish current activity in Android 7 answers Currently I'm starting a new Activity and calling finish on a current one. Is there any flag that can be passed to Intent that enables finishing current Activity without a need to call finish manually from code? You can use finish() method or you can use: android:noHistory="true" And then there is no need to call finish() anymore. <activity android:name=".ClassName" android:noHistory="true" ... /> Avi Kumar Manku Use finish like this: Intent i = new Intent(Main_Menu.this, NextActivity.class); finish()

I tried to scrub the GCC man page for this, but still don't get it, really. What's the difference between -march and -mtune ? When does one use just -march , vs. both? Is it ever possible to just -mtune ? If you use -march then GCC will be free to generate instructions that work on the specified CPU, but not on (typically) earlier CPUs in the architecture family. If you use -mtune , then the compiler will generate code that works on any of them, but will favour instruction sequences that run fastest on the specific CPU you indicated. This is what i've googled up: The -march=X option takes a

Why are people always using enum values like 0, 1, 2, 4, 8 and not 0, 1, 2, 3, 4 ? Has this something to do with bit operations, etc.? I would really appreciate a small sample snippet on how this is used correctly :) [Flags] public enum Permissions { None = 0, Read = 1, Write = 2, Delete = 4 } Because they are powers of two and I can do this: var permissions = Permissions.Read | Permissions.Write; And perhaps later... if( (permissions & Permissions.Write) == Permissions.Write ) { // we have write access } It is a bit field, where each set bit corresponds to some permission (or whatever the