大约有 47,000 项符合查询结果（耗时：0.0515秒） [XML]
Best way to test for a variable's existence in PHP; isset() is clearly broken
...l scope variables as well, on can do a $defined_vars = get_defined_vars(); and then test via array_key_exists('v', $defined_vars);.
– Henrik Opel
Sep 27 '10 at 16:01
1
...
Where's the difference between setObject:forKey: and setValue:forKey: in NSMutableDictionary?
...oking at the documentation, I hardly see any big difference. Both "value" and "object" are of type id , so can be any object. Key is once a string, and in the other case an id. One of them seems to retain the object, and the other don't. What else? Which one is for what case?
...
Conditional Variable vs Semaphore
When should one use a semaphore and when should one use a conditional variable (CondVar) ?
6 Answers
...
Visual Studio 2013 hangs when opening a solution
I installed VS2013 (v12.0.21005.1) and added ReSharper 8 (v8.0.2000.2660) a day or two ago. That day it was fine. Now I'm lucky if I can get it to open one solution in a whole day. It opens OK by itself, but when I try and open a solution from within - via the menu - it hangs, badly. If I right-clic...
Real world example about how to use property feature in python?
... interested in how to use @property in Python. I've read the python docs and the example there, in my opinion, is just a toy code:
...
ssh: Could not resolve hostname [hostname]: nodename nor servname provided, or not known
I am trying to set up a VPN with a Raspberry Pi, and the first step is gaining the ability to ssh into the device from outside my local network. For whatever reason, this is proving to be impossible and I haven't the slightest clue why. When I try to ssh into my server with user@hostname , I ge...
SQL Server NOLOCK and joins
Background: I have a performance-critical query I'd like to run and I don't care about dirty reads.
3 Answers
...
open read and close a file in 1 line of code
...lose it for various reasons.
So, what you can do to keep it short, simple and explicit:
with open('pagehead.section.htm','r') as f:
output = f.read()
Now it's just two lines and pretty readable, I think.
share
...
Why use symbols as hash keys in Ruby?
... basically "immutable strings" .. that means that they can not be changed, and it implies that the same symbol when referenced many times throughout your source code, is always stored as the same entity, e.g. has the same object id.
Strings on the other hand are mutable, they can be changed anytim...
How to efficiently compare two unordered lists (not sets) in Python?
... Hey @Raymond, I recently encountered this question on an interview and I used sorted(), admittedly not knowing about Counter. The interviewer insisted there was a more efficient method and clearly I drew a blank. After extensive testing in python 3 with the timeit module, sorted consisten...