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Why use ICollection and not IEnumerable or List on many-many/one-many relationships?
...ary/92t2ye13.aspx) for a list of objects that needs to be iterated through and modified, List<> for a list of objects that needs to be iterated through, modified, sorted, etc (See here for a full list: http://msdn.microsoft.com/en-us/library/6sh2ey19.aspx).
From a more specific standpoint, la...
Number of occurrences of a character in a string [duplicate]
...dibly expensive, if the string is large. Worst case if the string is large and (almost) entirely made up of repeated delimiters (&), it could allocate 12-24x the original size of the string due to object overheads in .Net. I would go with the second approach, and if that's not fast enough then w...
Are there any SHA-256 javascript implementations that are generally considered trustworthy?
...nst hashBuffer = await crypto.subtle.digest('SHA-256', msgBuffer);
// convert ArrayBuffer to Array
const hashArray = Array.from(new Uint8Array(hashBuffer));
// convert bytes to hex string
const hashHex = hashArray.map(b => ('00' + b.toString(16)).slice(-2)).joi...
How to map a composite key with JPA and Hibernate?
...y the specification also applies. So here they are:
2.1.4 Primary Keys and Entity Identity
...
A composite primary key must
correspond to either a single
persistent field or property or to a
set of such fields or properties as
described below. A primary key class
must be defi...
What exactly is a reentrant function?
...rant?
No.
For example, let's have a C++ function that takes both a lock, and a callback as a parameter:
#include <mutex>
typedef void (*callback)();
std::mutex m;
void foo(callback f)
{
m.lock();
// use the resource protected by the mutex
if (f) {
f();
}
// u...
Confusion between factor levels and factor labels
...reatment A etc.
The factor function will look for the values a, b and c, convert them to numerical factor classes, and add the label values to the level attribute of the factor. This attribute is used to convert the internal numerical values to the correct labels. But as you see, there is no label...
Set Django IntegerField by choices=… name
...bject. Hard to find with Google too so thanks.
– Alexander Ljungberg
Jul 13 '09 at 13:54
1
FWIW, ...
How to write log base(2) in c/c++
... log2 (x) = logy (x) / logy (2)
where y can be anything, which for standard log functions is either 10 or e.
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TypeError: 'dict_keys' object does not support indexing
...
Convert an iterable to a list may have a cost. Instead, to get the the first item, you can use:
next(iter(keys))
Or, if you want to iterate over all items, you can use:
items = iter(keys)
while True:
try:
item...
String contains - ignore case [duplicate]
...ks if CharSequence contains a search CharSequence irrespective of
case, handling null. Case-insensitivity is defined as by
String.equalsIgnoreCase(String).
A null CharSequence will return false.
This one will be better than regex as regex is always expensive in terms of performance.
For ...