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How can I quickly sum all numbers in a file?
...
For a Perl one-liner, it's basically the same thing as the awk solution in Ayman Hourieh's answer:
% perl -nle '$sum += $_ } END { print $sum'
If you're curious what Perl one-liners do, you can deparse them:
% perl -MO=Deparse -nle '$sum += $_ } END ...
Execution of Python code with -m option or not
...st python -m foo.bar.baz
foo.bar
__main__
As a result, Python has to actually care about packages when using the -m switch. A normal script can never be a package, so __package__ is set to None.
But run a package or module inside a package with -m and now there is at least the possibility of a pac...
What __init__ and self do on Python?
...to declare it explicitly. When you create an instance of the A class and call its methods, it will be passed automatically, as in ...
a = A() # We do not pass any argument to the __init__ method
a.method_a('Sailor!') # We only pass a single argument
The __init__ method is roughly w...
CSS hack大全 - 创意 - 清泛网 - 专注C/C++及内核技术
...io:0){.bb{background-color:#f1ee18}}{} /* Safari(Chrome) 有效 */
@media all and (min-width: 0px){ .bb{background-color:#f1ee18;/*opera and Safari(Chrome) and firefox*/ background-color:#4cac70\0;}/* 仅 Opera 有效 */ }{}
.bb, x:-moz-any-link, x:default{background-color:#4eff00;/*IE7、Firef...
Which $_SERVER variables are safe?
...ttacker can also control and is therefore a source of an attack. This is called a "tainted" variable, and is unsafe.
2 An...
Abstract classes in Swift Language
... importantly, notice that there is no dynamic dispatch. When logSalary is called on the instance that is stored as a SoftwareEngineer it calls the overridden version of the method. When logSalary is called on the instance after it has been cast to an Employee, it calls the original implementation (i...
How can mixed data types (int, float, char, etc) be stored in an array?
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@texasbruce also called a "tagged union". I'm using this technique too in my own language. ;)
– user529758
Sep 2 '13 at 16:50
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Python exit commands - why so many and when should each be used?
...s functionality was included to help people who do not know Python. After all, one of the most likely things a newbie will try to exit Python is typing in quit.
Nevertheless, quit should not be used in production code. This is because it only works if the site module is loaded. Instead, this fun...
Fast Bitmap Blur For Android SDK
...x Blur, but is
* 7x faster than my Gaussian Blur implementation.
*
* I called it Stack Blur because this describes best how this
* filter works internally: it creates a kind of moving stack
* of colors whilst scanning through the image. Thereby it
* just has to add one new block of color to th...
How do I count a JavaScript object's attributes? [duplicate]
...ry object in JavaScript derives from — includes many attributes automatically, and the exact set of attributes you get depends on the particular interpreter and what code has executed before yours. So, you somehow have to separate the ones you defined from those you got "for free."
Here's one way...