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Determine if a function exists in bash
Currently I'm doing some unit tests which are executed from bash. Unit tests are initialized, executed and cleaned up in a bash script. This script usualy contains an init(), execute() and cleanup() functions. But they are not mandatory. I'd like to test if they are or are not defined.
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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 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...
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...
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,...
What is “Argument-Dependent Lookup” (aka ADL, or “Koenig Lookup”)?
... editor after snippets, if snippets enabled
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How can I print literal curly-brace characters in python string and also use .format on it?
...expression in the brackets instead of using literal text you'll need three sets of brackets:
hello = "HELLO"
print(f"{{{hello.lower()}}}")
produces
{hello}
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PostgreSQL “DESCRIBE TABLE”
How do you perform the equivalent of Oracle's DESCRIBE TABLE in PostgreSQL (using the psql command)?
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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 ...