notation

Should I use single colons (:) or double colons (::) for before, after, first-letter and first-line pseudo-elements?

由 纵饮孤独 提交于 2019-11-26 12:27:44
问题 From MDN: The :: notation was introduced in CSS 3 in order to establish a discrimination between pseudo-classes and pseudo-elements. Browsers also accept the notation : introduced in CSS 2. If the notation : will always be accepted by CSS3 browsers, should I use it because it works on old and new browsers? Or should I use both of them, : for old browsers and :: for new ones, because the notation : won\'t be always accepted? Note : I think my question isn\'t a duplicate isn\'t a duplicate of

What is “?:” notation in JavaScript?

由 核能气质少年 提交于 2019-11-26 11:23:22
问题 I found this snippet of code in my travels in researching JSON: var array = typeof objArray != \'object\' ? JSON.parse(objArray) : objArray; I\'m seeing more and more of the ? and : notation. I don\'t even know what it is called to look it up! Can anyone point me to a good resource for this? (btw, I know what != means). 回答1: It's called a Conditional (ternary) Operator. It's essentially a condensed if-else. So this: var array = typeof objArray != 'object' ? JSON.parse(objArray) : objArray; ..

What exactly does += do in python?

由 我们两清 提交于 2019-11-26 10:14:54
I need to know what += does in python. It's that simple. I also would appreciate links to definitions of other short hand tools in python. Bryan In Python, += is sugar coating for the __iadd__ special method, or __add__ or __radd__ if __iadd__ isn't present. The __iadd__ method of a class can do anything it wants. The list object implements it and uses it to iterate over an iterable object appending each element to itself in the same way that the list's extend method does. Here's a simple custom class that implements the __iadd__ special method. You initialize the object with an int, then can

Compact MATLAB matrix indexing notation

由 雨燕双飞 提交于 2019-11-26 09:55:17
问题 I\'ve got an n-by-k sized matrix, containing k numbers per row. I want to use these k numbers as indexes into a k-dimensional matrix. Is there any compact way of doing so in MATLAB or must I use a for loop? This is what I want to do (in MATLAB pseudo code), but in a more MATLAB-ish way: for row=1:1:n finalTable(row) = kDimensionalMatrix(indexmatrix(row, 1),... indexmatrix(row, 2),...,indexmatrix(row, k)) end 回答1: If you want to avoid having to use a for loop, this is probably the cleanest way

What are the distinctions between the various symbols (*,&, etc) combined with parameters? [duplicate]

由 眉间皱痕 提交于 2019-11-26 08:31:33
问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: c++ * vs & in function declaration I know that this probably seems like an incredibly elementary question to many of you, but I have genuinely had an impossible time finding a good, thorough explanation, despite all my best Googling. I\'m certain that the answer is out there, and so my search terms must be terrible. In C++, a variety of symbols and combinations thereof are used to mark parameters (as well as

What's the difference between Git ignoring directory and directory/*?

由 两盒软妹~` 提交于 2019-11-26 08:05:04
问题 I\'m confused about what\'s the correct way to ignore the contents of a directory in git. Assume I have the following directory structure: my_project |--www |--1.txt |--2.txt |--.gitignore What\'s the difference between putting this: www And this? www/* The reason I\'m asking this question is: In git, if a directory is empty, git won\'t include such empty directory in repository. So I was trying the solution that is add an extra .gitkeep file under the directory so that it won\'t be empty.

What does %w(array) mean?

由 最后都变了- 提交于 2019-11-26 04:29:08
问题 I\'m looking at the documentation for FileUtils. I\'m confused by the following line: FileUtils.cp %w(cgi.rb complex.rb date.rb), \'/usr/lib/ruby/1.6\' What does the %w mean? Can you point me to the documentation? 回答1: %w(foo bar) is a shortcut for ["foo", "bar"] . Meaning it's a notation to write an array of strings separated by spaces instead of commas and without quotes around them. You can find a list of ways of writing literals in zenspider's quickref. 回答2: I think of %w() as a "word

What do numbers using 0x notation mean?

由 给你一囗甜甜゛ 提交于 2019-11-26 03:49:54
问题 What does a 0x prefix on a number mean? const int shared_segment_size = 0x6400; It\'s from a C program. I can\'t recall what it amounts to and particularly what the letter x means. 回答1: Literals that start with 0x are hexadecimal integers. (base 16) The number 0x6400 is 25600 . 6 * 16^3 + 4 * 16^2 = 25600 For an example including letters (also used in hexadecimal notation where A = 10, B = 11 ... F = 15) The number 0x6BF0 is 27632 . 6 * 16^3 + 11 * 16^2 + 15 * 16^1 = 27632 24576 + 2816 + 240

Bang Notation and Dot Notation in VBA and MS-Access

由 ☆樱花仙子☆ 提交于 2019-11-26 02:58:34
问题 While perusing an application that I\'m documenting, I\'ve run across some examples of bang notation in accessing object properties/methods, etc. and in other places they use dot notation for what seems like the same purpose. Is there a difference or preference to using one or the other? Some simple googling only reveals limited information on the subject with some people actually using it in opposite cases. Perhaps there is a coding standards section from MS somewhere that indicates the

What exactly does big Ө notation represent?

由 寵の児 提交于 2019-11-26 00:18:44
问题 I\'m really confused about the differences between big O, big Omega, and big Theta notation. I understand that big O is the upper bound and big Omega is the lower bound, but what exactly does big Ө (theta) represent? I have read that it means tight bound , but what does that mean? 回答1: It means that the algorithm is both big-O and big-Omega in the given function. For example, if it is Ө(n) , then there is some constant k , such that your function (run-time, whatever), is larger than n*k for
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