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What is the difference between “#!/usr/bin/env bash” and “#!/usr/bin/bash”?
...fferent systems. As long as it's in your path, it will find it.
One downside is that you will be unable to pass more than one argument (e.g. you will be unable to write /usr/bin/env awk -f) if you wish to support Linux, as POSIX is vague on how the line is to be interpreted, and Linux interprets e...
Difference between Big-O and Little-O Notation
...d ≤ 1
not ≤ 0, < 0, or < 1
Here's a table, showing the general idea:
(Note: the table is a good guide but its limit definition should be in terms of the superior limit instead of the normal limit. For example, 3 + (n mod 2) oscillates between 3 and 4 forever. It's in O(1) despite not...
Is calculating an MD5 hash less CPU intensive than SHA family functions?
...comparable efforts at optimizations; thus the speed differences can be considered as really intrinsic to the functions.
As a point of comparison, consider that a recent hard disk will run at about 100 MB/s, and anything over USB will top below 60 MB/s. Even though SHA-256 appears "slow" here, it is...
Understanding NSRunLoop
...
A run loop is an abstraction that (among other things) provides a mechanism to handle system input sources (sockets, ports, files, keyboard, mouse, timers, etc).
Each NSThread has its own run loop, which can be accessed via the currentRunLoop method.
In general, you do not need to ...
How do cache lines work?
... This answer makes absolutely no sense. What does the 64bit memory bandwidth (which is also wrong in that regard) to do with the 64 byte(!) not bit to do? Also the 10 to 30 ns are also totally wrong if you hit the Ram. It might be true for the L3 or L2 cache but not for the RAM where it is more l...
Scala type programming resources
...unction. Indeed, type-level programming makes heavy use of implicits.
Consider this example (taken from metascala and apocalisp):
sealed trait Nat
sealed trait _0 extends Nat
sealed trait Succ[N <: Nat] extends Nat
Here you have a peano encoding of the natural numbers. That is, you have a typ...
Multiprocessing - Pipe vs Queue
...='__main__':
for count in [10**4, 10**5, 10**6]:
# Pipes are unidirectional with two endpoints: p_input ------> p_output
p_output, p_input = Pipe() # writer() writes to p_input from _this_ process
reader_p = Process(target=reader_proc, args=((p_output, p_input),))
...
Transitioning from Windows Forms to WPF
...erms of UI components, not data objects. In addition, binding in WinForms didn't always exist in the state it does now, so many developers that grew up with WinForms, or who are used to other technologies that don't use bindings, will often not identify this key difference when switching to a bound ...
Different types of thread-safe Sets in Java
...er accesses which are running at this time continue with the old array, avoiding necessity of synchronization between readers and writers (though writing itself needs to be synchronized). The normally fast set operations (especially contains()) are quite slow here, as the arrays will be searched in ...
std::vector versus std::array in C++
...t grows and shrinks automatically if elements are added or removed. It provides all the hooks (begin(), end(), iterators, etc) that make it work fine with the rest of the STL. It also has several useful methods that let you perform operations that on a normal array would be cumbersome, like e.g. ins...