大约有 42,000 项符合查询结果（耗时：0.0595秒） [XML]
Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...f a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...
...
Copy existing project with a new name in Android Studio
I would like to copy my Android project and create a new project from the same files just with a different name. The purpose of this is so I can have a second version of my app which is ad supported in the app store.
...
What characters are allowed in an email address?
...
See RFC 5322: Internet Message Format and, to a lesser extent, RFC 5321: Simple Mail Transfer Protocol.
RFC 822 also covers email addresses, but it deals mostly with its structure:
addr-spec = local-part "@" domain ; global address
local-part ...
What is a software framework? [closed]
...o the measuring 1000 times; obviously, you would make a frame of 5m by 5m, and then with the help of it you would be able to cut 1000 pieces of paper in less time. So, what you did was make a framework which would do a specific type of task. Instead of performing the same type of task again and agai...
How can I profile C++ code running on Linux?
... a profiler, use one of the suggested ones.
However, if you're in a hurry and you can manually interrupt your program under the debugger while it's being subjectively slow, there's a simple way to find performance problems.
Just halt it several times, and each time look at the call stack. If there...
Why shouldn't I use “Hungarian Notation”?
...
Most people use Hungarian notation in a wrong way and are getting wrong results.
Read this excellent article by Joel Spolsky: Making Wrong Code Look Wrong.
In short, Hungarian Notation where you prefix your variable names with their type (string) (Systems Hungarian) is ba...
Comparing date ranges
In MySQL, If I have a list of date ranges (range-start and range-end). e.g.
10 Answers
...
Should I always use a parallel stream when possible?
With Java 8 and lambdas it's easy to iterate over collections as streams, and just as easy to use a parallel stream. Two examples from the docs , the second one using parallelStream:
...
Why do people say that Ruby is slow? [closed]
I like Ruby on Rails and I use it for all my web development projects. A few years ago there was a lot of talk about Rails being a memory hog and about how it didn't scale very well but these suggestions were put to bed by Gregg Pollack here.
...
Regular expression to check if password is “8 characters including 1 uppercase letter, 1 special cha
...
The regular expression you are after will most likely be huge and a nightmare to maintain especially for people who are not that familiar with regular expressions.
I think it would be easier to break your regex down and do it one bit at a time. It might take a bit more to do, but I am ...