大约有 47,000 项符合查询结果（耗时：0.0308秒） [XML]
How can I filter a date of a DateTimeField in Django?
...te operator. Check "#9596 Comparing a DateTimeField to a date is too hard" for more details.
share
|
improve this answer
|
follow
|
...
When should I use nil and NULL in Objective-C?
...ith an object.
if(str==nil)
NSLog("str is empty");
Now NULL is used for non-object pointer (like a C pointer) in Objective-C. Like nil , NULL got no value nor address.
char *myChar = NULL;
struct MyStruct *dStruct = NULL;
So if there is a situation, when I need to check my struct (structur...
JavaScript pattern for multiple constructors
I need different constructors for my instances. What is a common pattern for that?
9 Answers
...
How to determine a Python variable's type?
...
You may be looking for the type() built-in function.
See the examples below, but there's no "unsigned" type in Python just like Java.
Positive integer:
>>> v = 10
>>> type(v)
<type 'int'>
Large positive integer:
&g...
Should __init__() call the parent class's __init__()?
...er method is not strictly necessary, since the super method is empty. Same for __del__.
On the other hand, for __new__, you should indeed call the super method, and use its return as the newly-created object - unless you explicitly want to return something different.
...
Why can't I use a list as a dict key in python?
I'm a bit confused about what can/can't be used as a key for a python dict.
11 Answers
...
Does Python support short-circuiting?
... soon as a True is encountered and returns True.
>>> any(fun(i) for i in [1, 2, 3, 4]) # bool(1) = True
executed
True
>>> any(fun(i) for i in [0, 2, 3, 4])
executed # bool(0) = False
executed # bool(2) = True
True
&...
Random Gaussian Variables
...
Jarrett's suggestion of using a Box-Muller transform is good for a quick-and-dirty solution. A simple implementation:
Random rand = new Random(); //reuse this if you are generating many
double u1 = 1.0-rand.NextDouble(); //uniform(0,1] random doubles
double u2 = 1.0-rand...
What to put in a python module docstring? [closed]
... I've read both PEP 8 and PEP 257 , and I've written lots of docstrings for functions and classes, but I'm a little unsure about what should go in a module docstring. I figured, at a minimum, it should document the functions and classes that the module exports, but I've also seen a few modules t...
What is the difference between join and merge in Pandas?
...
pandas.merge() is the underlying function used for all merge/join behavior.
DataFrames provide the pandas.DataFrame.merge() and pandas.DataFrame.join() methods as a convenient way to access the capabilities of pandas.merge(). For example, df1.merge(right=df2, ...) is eq...