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Test if executable exists in Python?
In Python, is there a portable and simple way to test if an executable program exists?
21 Answers
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How does a PreparedStatement avoid or prevent SQL injection?
...g. But the input parameters will be sent to the database & appropriate cast/conversions will be applied prior to creating an actual SQL statement.
To give you an example, it might try and see if the CAST/Conversion works.
If it works, it could create a final statement out of it.
SELECT * Fr...
How to avoid overflow in expr. A * B - C * D
...ere's a work-around that only relies on implementation-defined behavior of casting unsigned integer to signed integer. But this can be expected to work on almost every system today.
(long long)((unsigned long long)A * B - (unsigned long long)C * D)
This casts the inputs to unsigned long long wher...
Covariance, Invariance and Contravariance explained in plain English?
...fferent generics parameters. Their relationships are the reason why we can cast them.
Co and Contra variance are pretty logical things. Language type system forces us to support real life logic. It's easy to understand by example.
Covariance
For instance you want to buy a flower and you have two ...
Using os.walk() to recursively traverse directories in Python
I want to navigate from the root directory to all other directories within and print the same.
13 Answers
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How does one generate a random number in Apple's Swift language?
...nteger between 0 and n-1.
let diceRoll = Int(arc4random_uniform(6) + 1)
Cast the result to Int so you don't have to explicitly type your vars as UInt32 (which seems un-Swifty).
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Calculating a directory's size using Python?
...= os.path.getsize(fp)
return total_size
print(get_size(), 'bytes')
And a oneliner for fun using os.listdir (Does not include sub-directories):
import os
sum(os.path.getsize(f) for f in os.listdir('.') if os.path.isfile(f))
Reference:
os.path.getsize - Gives the size in bytes
os.walk
os....
How to set environment variables in Python?
I need to set some environment variables in the Python script and I want all the other scripts that are called from Python to see the environment variables' set.
...
When would anyone use a union? Is it a remnant from the C-only days?
...pace.
We could use a wacky container of void* pointers to Bx objects with casts to retrieve them, but that's fugly and so C-style... but more importantly that would leave us with the lifetimes of many dynamically allocated objects to manage.
Instead, what can be done is this:
union Bee
{
B1 b...
Calculating the difference between two Java date instances
...oid. Rounding errors exist. Example 19th to 21st May says 1 day because it casts 1.99 to 1. Use round before casting to int.
– Pratik Mandrekar
May 1 '13 at 14:51
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