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Mapping two integers to one, in a unique and deterministic way
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You're looking for a bijective NxN -> N mapping. These are used for e.g. dovetailing. Have a look at this PDF for an introduction to so-called pairing functions. Wikipedia introduces a specific pairing function, namely the Cantor pairing...
What is the strict aliasing rule?
...r casting you can easily violate strict aliasing rules.
So in this kind of setup, if I want to send a message to something I'd have to have two incompatible pointers pointing to the same chunk of memory. I might then naively code something like this:
typedef struct Msg
{
unsigned int a;
unsi...
How can I reverse a NSArray in Objective-C?
...gure out why my A* algorithm was broken. It's because it returns the wrong set!
– Georg Schölly
Mar 12 '10 at 6:23
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How to generate random number with the specific length in python
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To get a random 3-digit number:
from random import randint
randint(100, 999) # randint is inclusive at both ends
(assuming you really meant three digits, rather than "up to three digits".)
To use an arbitrary number of digits:
from random import randin...
What is “Argument-Dependent Lookup” (aka ADL, or “Koenig Lookup”)?
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PostgreSQL “DESCRIBE TABLE”
How do you perform the equivalent of Oracle's DESCRIBE TABLE in PostgreSQL (using the psql command)?
22 Answers
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How do I grep recursively?
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grep -r "texthere" .
The first parameter represents the regular expression to search for, while the second one represents the directory that should be searched. In this case, . means the current directory.
Note: This works for GNU grep, and on some ...
What is the difference between a “function” and a “procedure”?
...om math. It is used to calculate a value based on input.
A procedure is a set of command which can be executed in order.
In most programming languages, even functions can have a set of commands. Hence the difference is only in the returning a value part.
But if you like to keep a function clean,...
how to calculate binary search complexity
...asymptotic growth of the time the function takes to execute given an input set of size n will not exceed log n.
This is just formal mathematical lingo in order to be able to prove statements, etc. It has a very straightforward explanation. When n grows very large, the log n function will out-grow t...
How to close this ssh tunnel? [closed]
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Assuming you ran this command: ssh -f user@mysql-server.com -L 3306:mysql-server.com:3306 -N as described in the post you linked.
A breakdown of the command:
ssh: that's pretty self-explanatory. Invokes ssh.
-f: (From the man ssh page)
Requests ssh to ...