大约有 40,000 项符合查询结果（耗时：0.0367秒） [XML]
How to achieve function overloading in C?
...sociation list that looks a bit like a switch block. _Generic gets the overall type of the expression and then "switches" on it to select the end result expression in the list for its type:
_Generic(1, float: 2.0,
char *: "2",
int: 2,
default: get_two_object());
...
How can a LEFT OUTER JOIN return more records than exist in the left table?
I have a very basic LEFT OUTER JOIN to return all results from the left table and some additional information from a much bigger table. The left table contains 4935 records yet when I LEFT OUTER JOIN it to an additional table the record count is significantly larger.
...
Is there a way to access method arguments in Ruby?
... "#{arg} = #{eval arg}" }.join(', ')
Note: since this answer was originally written, in current versions of Ruby eval can no longer be called with a symbol. To address this, an explicit to_s has been added when building the list of parameter names i.e. parameters.map { |arg| arg[1].to_s }
...
Geometric Mean: is there a built-in?
...pplication I had in mind they are the same, but of course this is not generally true. Thus, if you want to include optional propagation of zeros, and treat the length(x) differently in the case of NA removal, the following is a slightly longer alternative to the function above.
gm_mean = function(x...
How do you read CSS rule values with JavaScript?
I would like to return a string with all of the contents of a CSS rule, like the format you'd see in an inline style. I'd like to be able to do this without knowing what is contained in a particular rule, so I can't just pull them out by style name (like .style.width etc.)
...
Django ModelForm: What is save(commit=False) used for?
...
As a "real example", consider a user model where the email address and the username are always the same, and then you could overwrite your ModelForm's save method like:
class UserForm(forms.ModelForm):
...
def save(self):
# Sets username to email before saving
...
How to get the parents of a Python class?
...
If you want all the ancestors rather than just the immediate ones, use inspect.getmro:
import inspect
print inspect.getmro(cls)
Usefully, this gives you all ancestor classes in the "method resolution order" -- i.e. the order in which ...
Is it expensive to use try-catch blocks even if an exception is never thrown?
...
try has almost no expense at all. Instead of doing the work of setting up the try at runtime, the code's metadata is structured at compile time such that when an exception is thrown, it now does a relatively expensive operation of walking up the stack an...
What is the list of possible values for navigator.platform as of today? [closed]
...urate.
The definition
As far as I know there isn't a single public list of all possible `navigator.platform` values, even though the property has been around for quite a bit. To make things worse, the property's definition changed throughout the years. It used to be:
navigator.platform indicates th...
How do I find the location of Python module sources?
How do I learn where the source file for a given Python module is installed? Is the method different on Windows than on Linux?
...