大约有 11,287 项符合查询结果（耗时：0.0305秒） [XML]
What is the difference between square brackets and parentheses in a regex?
...:
/^(7|8|9)\d{9}$/
/^[789]\d{9}$/
/^[7-9]\d{9}$/
The explanation:
(a|b|c) is a regex "OR" and means "a or b or c", although the presence of brackets, necessary for the OR, also captures the digit. To be strictly equivalent, you would code (?:7|8|9) to make it a non capturing group.
[abc] is a...
What are the differences between “=” and “
What are the differences between the assignment operators = and <- in R?
7 Answers
...
How to replace list item in best way
I have replaced like above. Is there any other bestway to place compare than this one?
11 Answers
...
Assigning a variable NaN in python without numpy
Most languages have a NaN constant you can use to assign a variable the value NaN. Can python do this without using numpy?
...
Regular expression to match non-ASCII characters?
... a regex? I would like to match all words individually in an input string, but the language may not be English, so I will need to match things like ü, ö, ß, and ñ. Also, this is in Javascript/jQuery, so any solution will need to apply to that.
...
Convert a character digit to the corresponding integer in C
...sh to check isdigit(c) is true first. Note that you cannot completely portably do the same for letters, for example:
char c = 'b';
int x = c - 'a'; // x is now not necessarily 1
The standard guarantees that the char values for the digits '0' to '9' are contiguous, but makes no guarantees for othe...
Re-open *scratch* buffer in Emacs?
If I accidentally closed the scratch buffer in Emacs, how do I create a new scratch buffer?
16 Answers
...
Java 8 Streams - collect vs reduce
...duce() ? Does anyone have good, concrete examples of when it's definitely better to go one way or the other?
7 Answers
...
Difference between variable declaration syntaxes in Javascript (including global variables)?
Is there any difference between declaring a variable:
5 Answers
5
...
HTML5 Pre-resize images before uploading
...en you can process the images with the canvas element.
This Mozilla Hacks blog post walks you through most of the process. For reference here's the assembled source code from the blog post:
// from an input element
var filesToUpload = input.files;
var file = filesToUpload[0];
var img = document....