大约有 40,000 项符合查询结果（耗时：0.0514秒） [XML]
Why does !{}[true] evaluate to true in JavaScript?
...undefined) must therefore be defined. If something is defined then it's usually interpreted as true.
– OozeMeister
Oct 31 '13 at 16:50
7
...
Drop unused factor levels in a subsetted data frame
...tion, a new data frame is created. However, the factor variable retains all of its original levels, even when/if they do not exist in the new dataframe.
...
Calling a Java method with no name
... System.out.print("x ");
}
is a static initialization block, and is called when the class is loaded. You can have as many of them in your class as you want, and they will be executed in order of their appearance (from top to bottom).
This:
{
System.out.print("y ");
}
is an ...
How do I use valgrind to find memory leaks?
...o come to this question and are still new to Linux—you might have to install Valgrind on your system.
sudo apt install valgrind # Ubuntu, Debian, etc.
sudo yum install valgrind # RHEL, CentOS, Fedora, etc.
Valgrind is readily usable for C/C++ code, but can even be used for other
languages wh...
git reset --hard HEAD leaves untracked files behind
...rking copy.
If you need to reset the whole repository to master including all git submodules, run this script:
git reset --hard HEAD
git clean -f -d
git checkout master
git fetch origin master
git reset --hard origin/master
git pull
git submodule update
git submodule update --init --recursive
git ...
Python memory leaks [closed]
... have a long-running script which, if let to run long enough, will consume all the memory on my system.
9 Answers
...
Calling a base class's classmethod in Python
...asses, which derive from object. (at least in Python 2, but in Py3 I think all classes are new-style, IIRC) Otherwise you have to do Base.do(self, ...), I think, thereby hard-coding the name of the superclass.
– David Z
Jun 11 '14 at 19:29
...
How do I syntax check a Bash script without running it?
...is documented, and as the beginning of the manpage states, bash interprets all single-character options that set does.
– ephemient
Oct 5 '08 at 20:55
24
...
How to pass optional arguments to a method in C++?
... do_something();
else
do_something_else();
}
you can call myfunc in both ways and both are valid
myfunc(10); // Mode will be set to default 0
myfunc(10, 1); // Mode will be set to 1
share
...
How can I generate a unique ID in Python? [duplicate]
...in newer versions, but most people probably don't have that yet, so I generally avoid this module. Caused me major headaches with listen sockets...
– Glenn Maynard
Jul 31 '09 at 3:14
...