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C# How can I check if a URL exists/is valid?
...e.g. images, files etc) HEAD usually works as advertised since it is baked into the server. Many programmers do not explicitly HEAD requests since the focus is normally on POST and GET. YMMV
– David Taylor
May 29 '09 at 15:53
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How to resume Fragment from BackStack if exists
...ment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
}
}
EDIT
The problem is - when i launch A and then B, then press back button, B
is removed and ...
Primary key or Unique index?
...index on a column is an index on that column that also enforces the constraint that you cannot have two equal values in that column in two different rows. Example:
CREATE TABLE table1 (foo int, bar int);
CREATE UNIQUE INDEX ux_table1_foo ON table1(foo); -- Create unique index on foo.
INSERT INTO...
Performance of Java matrix math libraries? [closed]
...thing whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question:
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Is there a regular expression to detect a valid regular expression?
...n directly. (The (?1) and (?R) constructs.) The recursion would have to be converted to counting balanced groups:
^ # start of string
(?:
(?: [^?+*{}()[\]\\|]+ # literals and ^, $
| \\. # escaped charact...
Label encoding across multiple columns in scikit-learn
...
We don't need a LabelEncoder.
You can convert the columns to categoricals and then get their codes. I used a dictionary comprehension below to apply this process to every column and wrap the result back into a dataframe of the same shape with identical indices a...
Check if a string matches a regex in Bash script
...is in the correct format, it is best to parse it with date and ask date to convert the string to the correct format. If both strings are identical, you have a valid format and valid date.
if [[ "$datestr" == $(date -d "$datestr" "+%Y%m%d" 2>/dev/null) ]]; then
echo "Valid date"
else
e...
C# nullable string error
...nullable".
Nullable<T> and the ? suffix are for value types such as Int32, Double, DateTime, etc.
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Example of UUID generation using Boost in C++
...important for instances in my program to have unique identifiers. I looked into Boost UUID , but I can't manage to generate the UUID because I don't understand which class and method to use.
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How to check whether an array is empty using PHP?
...er(): If no callback is supplied, all entries of array equal to FALSE (see converting to boolean) will be removed.
If you'd like to remove all NULL, FALSE and empty strings (''), but leave zero values (0), you can use strlen as a callback, e.g.:
$is_empty = array_filter($playerlist, 'strlen') == ...