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Subtract two variables in Bash
...
You just need a little extra whitespace around the minus sign, and backticks:
COUNT=`expr $FIRSTV - $SECONDV`
Be aware of the exit status:
The exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null or 0.
Keep this in min...
How to read XML using XPath in Java
...er = factory.newDocumentBuilder();
Document doc = builder.parse(<uri_as_string>);
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile(<xpath_expression>);
Then you call expr.evaluate() passing in the docume...
How can I auto-elevate my batch file, so that it requests from UAC administrator rights if required?
...Note that you need to use for to be able to take advantage of the advanced string functions, such as %%~nk, which extracts just the filename.
Optimized script structure, improvements (added variable vbsGetPrivileges which is now referenced everywhere allowing to change the path or name of the file e...
python list in sql query as parameter
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Answers so far have been templating the values into a plain SQL string. That's absolutely fine for integers, but if we wanted to do it for strings we get the escaping issue.
Here's a variant using a parameterised query that would work for both:
placeholder= '?' # For SQLite. See DBAPI p...
What's the longest possible worldwide phone number I should consider in SQL varchar(length) for phon
... as the limit ... without formatting. Adding formatting may add roughly an extra character for every digit. So as a final thought it may not be a good idea to limit the phone number in the database in any way and leave shorter limits to the UX designers.
...
encryption/decryption with multiple keys
..., AES-NI, to do some steps of the algorithm in hardware, which makes GnuPG extra snappy at encrypting/decrypting data.
Another reason for doing it this way is that it allows PGP-encrypted documents to be encrypted to multiple parties without having to double the size of the document. Notice that w...
Immutable vs Mutable types
...o
x = 5.0
x += 7.0
print x # 12.0
Doesn't that "mut" x?
Well you agree strings are immutable right? But you can do the same thing.
s = 'foo'
s += 'bar'
print s # foobar
The value of the variable changes, but it changes by changing what the variable refers to. A mutable type can change that wa...
What does [object Object] mean?
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The default conversion from an object to string is "[object Object]".
As you are dealing with jQuery objects, you might want to do
alert(whichIsVisible()[0].id);
to print the element's ID.
As mentioned in the comments, you should use the tools included in brows...
Manually raising (throwing) an exception in Python
...older versions of Python (2.4 and lower), you may still see people raising strings:
raise 'message' # really really wrong. don't do this.
In all modern versions, this will actually raise a TypeError, because you're not raising a BaseException type. If you're not checking for the right exception a...
Will the base class constructor be automatically called?
... a need to call the one with parameters:
class Person
{
public Person(string random)
{
}
}
class Customer : Person
{
public Customer(string random) : base (random)
{
}
}
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