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How to initialize all members of an array to the same value?
...e same value, without multiple copy-paste, you can use macros:
#define VAL_1X 42
#define VAL_2X VAL_1X, VAL_1X
#define VAL_4X VAL_2X, VAL_2X
#define VAL_8X VAL_4X, VAL_4X
#define VAL_16X VAL_8X, VAL_8X
#define VAL_32X VAL_16X, VAL_16X
#define VAL_64X VAL_32X, VAL_32X
i...
Concurrent HashSet in .NET Framework?
...byte (1 byte in memory).
private ConcurrentDictionary<string, byte> _data;
This is the recommended option because the type is thread-safe and provide you the same advantages than a HashSet<T> except key and value are different objects.
Source: Social MSDN
ConcurrentBag
If you don't...
How to override the [] operator in Python?
...
You need to use the __getitem__ method.
class MyClass:
def __getitem__(self, key):
return key * 2
myobj = MyClass()
myobj[3] #Output: 6
And if you're going to be setting values you'll need to implement the __setitem__ method too,...
Difference between a theta join, equijoin and natural join
... yourself).
** I don't quite know what the result of SELECT * FROM table_expression; is. I know it is not a relation because, among other reasons, it can have columns with duplicate names or a column with no name. I know it is not a set because, among other reasons, the column order is significan...
6个变态的C语言Hello World程序 - 创意 - 清泛网 - 专注C/C++及内核技术
...要动用C++的编译器g++才能编程通过。
hello1.c
#define _________ }
#define ________ putchar
#define _______ main
#define _(a) ________(a);
#define ______ _______(){
#define __ ______ _(0x48)_(0x65)_(0x6C)_(0x6C)
#define ___ _(0x6F)_(0x2C)_(0x20)_(0x77)_(0x6F)
#define ____ _...
Django filter queryset __in for *every* item in list
...oManyField('Tag')
class Tag(models.Model):
name = models.CharField(max_length=50)
def __unicode__(self):
return self.name
In [2]: t1 = Tag.objects.create(name='holiday')
In [3]: t2 = Tag.objects.create(name='summer')
In [4]: p = Photo.objects.create()
In [5]: p.tags.add(t1)
In [6]...
Creating a dynamic choice field
...passing the user to the form init
class waypointForm(forms.Form):
def __init__(self, user, *args, **kwargs):
super(waypointForm, self).__init__(*args, **kwargs)
self.fields['waypoints'] = forms.ChoiceField(
choices=[(o.id, str(o)) for o in Waypoint.objects.filter(use...
MIN and MAX in C
...afety bonus too) in a GCC statement expression:
#define max(a,b) \
({ __typeof__ (a) _a = (a); \
__typeof__ (b) _b = (b); \
_a > _b ? _a : _b; })
Everyone says "oh I know about double evaluation, it's no problem" and a few months down the road, you'll be debugging the silliest ...
Why does Python code use len() function instead of a length method?
...
Strings do have a length method: __len__()
The protocol in Python is to implement this method on objects which have a length and use the built-in len() function, which calls it for you, similar to the way you would implement __iter__() and use the built-in ...
What does “hashable” mean in Python?
...if it has a hash value which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() or __cmp__() method). Hashable objects which compare equal must have the same hash value.
Hashability makes an object usable as a dictionary ...