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What is the point of a private pure virtual function?
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The question in the topic suggest a pretty common confusion. The confusion is common enough, that C++ FAQ advocated against using private virtuals, for a long time, because confusion seemed to be a bad thing.
So to get rid of the confusion first: Yes, private virtual...
Solving a “communications link failure” with JDBC and MySQL [duplicate]
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I have had the same problem in two of my programs. My error was this:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
I spent ...
When do you use Java's @Override annotation and why?
...de a method for two benefits. Do it so that you can take advantage of the compiler checking to make sure you actually are overriding a method when you think you are. This way, if you make a common mistake of misspelling a method name or not correctly matching the parameters, you will be warned tha...
How to validate IP address in Python? [duplicate]
...at's the best way to validate that an IP entered by the user is valid? It comes in as a string.
11 Answers
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What requirement was the tuple designed to solve?
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When writing programs it is extremely common to want to logically group together a set of values which do not have sufficient commonality to justify making a class.
Many programming languages allow you to logically group together a set of otherwise unrelated v...
SqlException from Entity Framework - New transaction is not allowed because there are other threads
...ach (RivWorks.Model.NegotiationAutos.Client client in clientList)
{
var companyFeedDetailList = from a in _dbRiv.AutoNegotiationDetails where a.ClientID == client.ClientID select a;
// ...
}
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How can I check if a program exists from a Bash script?
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Answer
POSIX compatible:
command -v <the_command>
Example use:
if ! command -v COMMAND &> /dev/null
then
echo "COMMAND could not be found"
exit
fi
For Bash specific environments:
hash <the_command> # For regul...
When to use Common Table Expression (CTE)
I have begun reading about Common Table Expression and cannot think of a use case where I would need to use them. They would seem to be redundant as the same can be done with derived tables. Is there something I am missing or not understanding well? Can someone give me a simple example of limitati...
Is there a Java reflection utility to do a deep comparison of two objects?
...where that is capable of taking two objects of the same type, doing a deep comparison, and saying if they're identical or not?
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How can I propagate exceptions between threads?
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