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Regex that accepts only numbers (0-9) and NO characters [duplicate]
...nning with a digit, including strings like "1A". To avoid a partial match, append a $ to the end:
^[0-9]*$
This accepts any number of digits, including none. To accept one or more digits, change the * to +. To accept exactly one digit, just remove the *.
UPDATE: You mixed up the arguments to IsM...
Why is the Java main method static?
...vention.
When you run java.exe (or javaw.exe on Windows), what is really happening is a couple of Java Native Interface (JNI) calls. These calls load the DLL that is really the JVM (that's right - java.exe is NOT the JVM). JNI is the tool that we use when we have to bridge the virtual machine wor...
Preloading images with JavaScript
...OP:
var preloadImage = function (url) {
try {
var _img = new Image();
_img.src = url;
} catch (e) { }
}
Standard:
function preloadImage (url) {
try {
var _img = new Image();
_img.src = url;
} catch (e) { ...
What is a regular expression for a MAC Address?
...perty \p{xdigit} includes the FULLWIDTH versions. You might prefer \p{ASCII_Hex_Digit} instead.
The answer to the question asked might be best answered — provided you have a certain venerable CPAN module installed — by typing:
% perl -MRegexp::Common -lE 'say $RE{net}{MAC}'
I show the partic...
What's the difference between lists and tuples?
...e pairs of page and line number to reference locations in a book, e.g.:
my_location = (42, 11) # page number, line number
You can then use this as a key in a dictionary to store notes on locations. A list on the other hand could be used to store multiple locations. Naturally one might want to ad...
What is Java String interning?
...nterning is implemented magically and efficiently with a dedicated CONSTANT_String_info struct (unlike most other objects which have more generic representations):
A string literal is a reference to an instance of class String, and is derived from a CONSTANT_String_info structure (§4.4.3) in th...
Iterate over the lines of a string
...< 0: break
yield foo[prevnl + 1:nextnl]
prevnl = nextnl
if __name__ == '__main__':
for f in f1, f2, f3:
print list(f())
Running this as the main script confirms the three functions are equivalent. With timeit (and a * 100 for foo to get substantial strings for more precise me...
Styling multi-line conditions in 'if' statements? [closed]
...nd cond2 == 'val2' and
cond3 == 'val3' and cond4 == 'val4'):
do_something
Also, don't forget the whitespace is more flexible than you might think:
if (
cond1 == 'val1' and cond2 == 'val2' and
cond3 == 'val3' and cond4 == 'val4'
):
do_something
if (cond1 == ...
Is jquery a javascript library or framework? [closed]
...e-framework:
It is a collection of software libraries providing a defined
application programming interface.
And jQuery is just a single library. After that it says:
Frameworks contain key distinguishing features that separate them from normal libraries:
inversion of control - In a framework, un...
What characters are valid for JavaScript variable names?
...mmarizing the relevant spec sections:
An identifier must start with $, _, or any character in the Unicode categories “Uppercase letter (Lu)”, “Lowercase letter (Ll)”, “Titlecase letter (Lt)”, “Modifier letter (Lm)”, “Other letter (Lo)”, or “Letter number (Nl)”.
The r...