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How can I check if a file exists in Perl?
... given path using the -e file-test operator.
print "$base_path exists!\n" if -e $base_path;
However, this test is probably broader than you intend. The code above will generate output if a plain file exists at that path, but it will also fire for a directory, a named pipe, a symlink, or a more ex...
Jinja2 template variable if None Object set a default value
How to make a variable in jijna2 default to "" if object is None instead of doing something like this?
9 Answers
...
How to convert number to words in java
...= {
"",
" ten",
" twenty",
" thirty",
" forty",
" fifty",
" sixty",
" seventy",
" eighty",
" ninety"
};
private static final String[] numNames = {
"",
" one",
" two",
" three",
" four",
" five",
" six",
" seven",
" eigh...
How can I check if a key exists in a dictionary? [duplicate]
...
if key in array:
# do something
Associative arrays are called dictionaries in Python and you can learn more about them in the stdtypes documentation.
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Is there a Python equivalent of the C# null-coalescing operator?
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other = s or "some default value"
Ok, it must be clarified how the or operator works. It is a boolean operator, so it works in a boolean context. If the values are not boolean, they are converted to boolean for the purposes of the operator.
Note that the or operator does not r...
Best way to “negate” an instanceof
I was thinking if there exists a better/nicer way to negate an instanceof in Java.
Actually, I'm doing something like:
9 ...
Finding Number of Cores in Java
...
int cores = Runtime.getRuntime().availableProcessors();
If cores is less than one, either your processor is about to die, or your JVM has a serious bug in it, or the universe is about to blow up.
share
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Whether a variable is undefined [duplicate]
How do I find if a variable is undefined?
5 Answers
5
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When should an IllegalArgumentException be thrown?
... 'recover' from this exception by providing an error message to the user.
If the input originates from your own system, e.g. your database, or some other parts of your application, you should be able to rely on it to be valid (it should have been validated before it got there). In this case it's pe...
Why does Path.Combine not properly concatenate filenames that start with Path.DirectorySeparatorChar
... it's doing exactly what the documentation says.
System.IO.Path.Combine
"If path2 contains an absolute path, this method returns path2."
Here's the actual Combine method from the .NET source. You can see that it calls CombineNoChecks, which then calls IsPathRooted on path2 and returns that path ...