大约有 16,000 项符合查询结果（耗时：0.0376秒） [XML]
Which iomanip manipulators are 'sticky'?
I recently had a problem creating a stringstream due to the fact that I incorrectly assumed std::setw() would affect the stringstream for every insertion, until I changed it explicitly. However, it is always unset after the insertion.
...
PostgreSQL: Can you create an index in the CREATE TABLE definition?
I want to add indexes to some of the columns in a table on creation. Is there are way to add them to the CREATE TABLE definition or do I have to add them afterward with another query?
...
'git add --patch' to include new files?
When I run git add -p , is there a way for git to select newly made files as hunks to select??
5 Answers
...
When should you not use virtual destructors?
...
There is no need to use a virtual destructor when any of the below is true:
No intention to derive classes from it
No instantiation on the heap
No intention to store in a pointer of a superclass
No specific reason to avoid it unless you are really so pressed for memory.
...
select * vs select column
If I just need 2/3 columns and I query SELECT * instead of providing those columns in select query, is there any performance degradation regarding more/less I/O or memory?
...
How to keep a git branch in sync with master
At the moment git is doing my head in, I cannot come up with the best solution for the following.
6 Answers
...
Control the size of points in an R scatterplot?
In R, the plot() function takes a pch argument that controls the appearance of the points in the plot. I'm making scatterplots with tens of thousands of points and prefer a small, but not too small dot. Basically, I find pch='.' to be too small, but pch=19 to be too fat. Is there somethin...
Why doesn't Objective-C support private methods?
I've seen a number of strategies for declaring semi-private methods in Objective-C , but there does not seem to be a way to make a truly private method. I accept that. But, why is this so? Every explanation I've essentially says, "you can't do it, but here's a close approximation."
...
Can someone explain Microsoft Unity?
I've been reading the articles on MSDN about Unity (Dependency Injection, Inversion of Control), but I think I need it explained in simple terms (or simple examples). I'm familiar with the MVPC pattern (we use it here), but I just can't really grasp this Unity thing yet, and I think it's the next st...
Assignment inside lambda expression in Python
I have a list of objects and I want to remove all objects that are empty except for one, using filter and a lambda expression.
...