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How to check if a number is a power of 2
...eturn (x != 0) && ((x & (x - 1)) == 0);
}
Explanation
First and foremost the bitwise binary & operator from MSDN definition:
Binary & operators are predefined for the integral types and bool. For
integral types, & computes the logical bitwise AND of its operands.
F...
Log to the base 2 in python
....log(x, 2.0)
log2 = math.log2(x) # python 3.4 or later
Thanks @akashchandrakar and @unutbu.
float → int math.frexp(x)
If all you need is the integer part of log base 2 of a floating point number, extracting the exponent is pretty efficient:
log2int_slow = int(math.floor(math.log(x, 2.0)...
Replace console output in Python
...
An easy solution is just writing "\r" before the string and not adding a newline; if the string never gets shorter this is sufficient...
sys.stdout.write("\rDoing thing %i" % i)
sys.stdout.flush()
Slightly more sophisticated is a progress bar... this is something I am using:
d...
How can I remove an element from a list?
I have a list and I want to remove a single element from it. How can I do this?
16 Answers
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What causes and what are the differences between NoClassDefFoundError and ClassNotFoundException?
What is the difference between NoClassDefFoundError and ClassNotFoundException ?
15 Answers
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overlay opaque div over youtube iframe
...windowed which essentially gives it a z-index greater then everything else and it will overlay over anything.
Try appending this GET parameter to your URL:
wmode=opaque
like so:
https://www.youtube.com/embed/kRvL6K8SEgY?wmode=opaque
Make sure its the first parameter in the URL. Other paramete...
How can a Java variable be different from itself?
...same with Double.NaN.
From JLS §15.21.1. Numerical Equality Operators == and !=:
Floating-point equality testing is performed in accordance with the rules of the IEEE 754 standard:
If either operand is NaN, then the result of == is false but the result of != is true.
Indeed, the test x!=x is tru...
Difference between object and class in Scala
I'm just going over some Scala tutorials on the Internet and have noticed in some examples an object is declared at the start of the example.
...
boost::flat_map and its performance compared to map and unordered_map
...haven't been able to find any performance comparisons. How does it compare and what are the best use cases for it?
2 Answer...
Can I install Python 3.x and 2.x on the same Windows computer?
I'm running Windows and the shell/OS automatically runs Python based on the registry settings when you run a program on the command line. Will this break if I install a 2.x and 3.x version of Python on the same machine?
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