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When should we use mutex and when should we use semaphore
When should we use mutex and when should we use semaphore ?
12 Answers
12
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Difference between del, remove and pop on lists
...;>> a = [9, 8, 7, 6]
>>> del a[1]
>>> a
[9, 7, 6]
and pop removes the item at a specific index and returns it.
>>> a = [4, 3, 5]
>>> a.pop(1)
3
>>> a
[4, 5]
Their error modes are different too:
>>> a = [4, 5, 6]
>>> a.remove(7)
T...
Algorithm to calculate the number of divisors of a given number
...st of primes you'll need to see how many of those primes act as a divisor (and how often).
Here's some python for the algo Look here and search for "Subject: math - need divisors algorithm". Just count the number of items in the list instead of returning them however.
Here's a Dr. Math that explai...
Fastest way to check if a string matches a regexp in ruby?
... avoids object allocations performed by other methods such as Regexp#match and =~:
Regexp#match?
Added Regexp#match?, which executes a regexp match without creating a back reference object and changing $~ to reduce object allocation.
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Is mathematics necessary for programming? [closed]
...al knowledge from high school or fresh year college math, no more no less, and that almost all of programming tasks can be achieved without even need for advanced math. He argued, however, that algorithms are fundamental & must-have asset for programmers.
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Can you change what a symlink points to after it is created?
Does any operating system provide a mechanism (system call — not command line program) to change the pathname referenced by a symbolic link (symlink) — other than by unlinking the old one and creating a new one?
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finding and replacing elements in a list
I have to search through a list and replace all occurrences of one element with another. So far my attempts in code are getting me nowhere, what is the best way to do this?
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Why do indexes in XPath start with 1 and not 0?
Some colleagues and I were comparing past languages we had programmed in and were talking about our experience with VBScript with its odd features such as 1-based index instead of 0-based indexes like almost every other language has, the reasoning being that it was a language for users (e.g....
Why are floating point numbers inaccurate?
...t numbers are represented a lot like scientific notation: with an exponent and a mantissa (also called the significand). A very simple number, say 9.2, is actually this fraction:
5179139571476070 * 2 -49
Where the exponent is -49 and the mantissa is 5179139571476070. The reason it is impossibl...
How does C compute sin() and other math functions?
I've been poring through .NET disassemblies and the GCC source code, but can't seem to find anywhere the actual implementation of sin() and other math functions... they always seem to be referencing something else.
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