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'is' versus try cast with null check
...// only one cast
if (myObjRef != null)
{
// myObjRef is already MyType and doesn't need to be cast again
...
}
C# 7.0 supports a more compact syntax using pattern matching:
if (myObj.myProp is MyType myObjRef)
{
...
}
...
Seeing escape characters when pressing the arrow keys in python shell
... use the arrow keys to move around in the current line or get previous commands (with arrow-up) etc.
23 Answers
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No module named MySQLdb
I am using Python version 2.5.4 and install MySQL version 5.0 and Django. Django is working fine with Python, but not MySQL. I am using it in Windows Vista.
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Optimise PostgreSQL for fast testing
.... For example, PostgreSQL 9.2 significantly improves the speed of TRUNCATE and of course adds index-only scans. Even minor releases should always be followed; see the version policy.
Don'ts
Do NOT put a tablespace on a RAMdisk or other non-durable storage.
If you lose a tablespace the whole datab...
Can't find the 'libpq-fe.h header when trying to install pg gem
...nx), 11.10 (Oneiric Ocelot), 12.04 (Precise Pangolin), 14.04 (Trusty Tahr) and 18.04 (Bionic Beaver)):
...
/usr/include/postgresql/libpq-fe.h
...
So try installing libpq-dev or its equivalent for your OS:
For Ubuntu/Debian systems: sudo apt-get install libpq-dev
On Red Hat Linux (RHEL) systems:...
How to check status of PostgreSQL server Mac OS X
...e simplest way to to check running processes:
ps auxwww | grep postgres
And look for a command that looks something like this (your version may not be 8.3):
/Library/PostgreSQL/8.3/bin/postgres -D /Library/PostgreSQL/8.3/data
To start the server, execute something like this:
/Library/PostgreS...
Graph Algorithm To Find All Connections Between Two Arbitrary Vertices
...l non-cyclical paths between two nodes. This algorithm should be very fast and scale to large graphs (The graph data structure is sparse so it only uses as much memory as it needs to).
I noticed that the graph you specified above has only one edge that is directional (B,E). Was this a typo or is it...
When NOT to use yield (return) [duplicate]
... this O(n) times for a tree with n items, that makes the algorithm O(hn). And since the height of a binary tree is lg n <= h <= n, that means that the algorithm is at best O(n lg n) and at worst O(n^2) in time, and best case O(lg n) and worse case O(n) in stack space. It is O(h) in heap space...
How do I measure request and response times at once using cURL?
... have a web service that receives data in JSON format, processes the data, and then returns the result to the requester.
14...
Write a function that returns the longest palindrome in a given string
...ng Manacher's Algorithm in O(n) time! Its implementation can be found here and here.
For input String s = "HYTBCABADEFGHABCDEDCBAGHTFYW1234567887654321ZWETYGDE" it finds the correct output which is 1234567887654321.
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