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Check if a Class Object is subclass of another Class Object in Java
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if (o instanceof Number) {
double d = ((Number)o).doubleValue(); //this cast is safe
}
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Setting the correct encoding when piping stdout in Python
...t of a Python program, the Python interpreter gets confused about encoding and sets it to None. This means a program like this:
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Allowed characters in Linux environment variable names
...llowed in Linux environment variable names? My cursory search of man pages and the web did only produce information about how to work with variables, but not which names are allowed.
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How do I specify the Linq OrderBy argument dynamically?
...method to be an IOrderedQueryable instead of an IQueryable, you can simply cast the result as follows:
public static IOrderedQueryable<TEntity> OrderBy<TEntity>(this IQueryable<TEntity> source, string orderByProperty, bool desc)
{
string command = desc ? "OrderByDescending" :...
Sending email with PHP from an SMTP server
...l through a server that requires SMTP Auth, you really need to specify it, and set the host, username and password (and maybe the port if it is not the default one - 25).
For example, I usually use PHPMailer with similar settings to this ones:
$mail = new PHPMailer();
// Settings
$mail->IsSMTP...
Quickly create a large file on a Linux system
...her answers is a good solution, but it is slow for this purpose. In Linux (and other POSIX systems), we have fallocate, which uses the desired space without having to actually writing to it, works with most modern disk based file systems, very fast:
For example:
fallocate -l 10G gentoo_root.img
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Best way to get identity of inserted row?
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Add
SELECT CAST(scope_identity() AS int);
to the end of your insert sql statement, then
NewId = command.ExecuteScalar()
will retrieve it.
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How to do an instanceof check with Scala(Test)
...r needs. I would recommend it in those cases because it gives you the typecasting for free and leaves less room for error.
Example:
OuterType foo = blah
foo match {
case subFoo : SubType => {
subFoo.thingSubTypeDoes // no need to cast, use match variable
}
case subFoo => {
// ...
Select between two dates with Django
... Filtering with dates won’t include items on the last day.
You need to casts the value as date:
...filter(created_at__date__range=(start_date, end_date))
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How to avoid the “divide by zero” error in SQL?
...of the first argument. This altered example works fine: SELECT 1 / NULLIF(CAST(NULL AS INT), 0). In real life, you are going to supply a table column to NULLIF() rather than a NULL constant. Since table columns have known datatypes, this also works fine: SELECT 1 / NULLIF(SomeNullableColumn, 0) F...