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What is the lifetime of a static variable in a C++ function?
... scope it is only initialized once and retains its value between function calls. What exactly is its lifetime? When do its constructor and destructor get called?
...
How to solve error “Missing `secret_key_base` for 'production' environment” (Rails 4.1)
...and Enter for save and exit in vi.
But if you login as normal user, let's call it "example_user" for this gist, you will need to find one of these other files:
$ vi ~/.bash_profile
$ vi ~/.bash_login
$ vi ~/.profile
These files are in order of importance, which means that if you have the first fi...
Should I pass an std::function by const-reference?
...rmance, pass by value if you are storing it.
Suppose you have a function called "run this in the UI thread".
std::future<void> run_in_ui_thread( std::function<void()> )
which runs some code in the "ui" thread, then signals the future when done. (Useful in UI frameworks where the UI ...
How to declare a structure in a header that is to be used by multiple files in c?
...ting it in an header file, and include this header file whenever needed.
shall we open a new header file and declare the structure there and include that header in the func.c?
This is the solution I like more, because it makes the code highly modular. I would code your struct as:
#ifndef SOME_HEADER...
Why does casting int to invalid enum value NOT throw exception?
...is backed by another value type (int, short, byte, etc), and so it can actually have any value that is valid for those value types.
I personally am not a fan of the way this works, so I made a series of utility methods:
/// <summary>
/// Utility methods for enum values. This static type will...
Android: How can I pass parameters to AsyncTask's onPreExecute()?
...
// do stuff
}
// doInBackground() et al.
}
Then, when calling the task, do something like:
new MyAsyncTask(true).execute(maybe_other_params);
Edit: this is more useful than creating member variables because it simplifies the task invocation. Compare the code above with:
MyA...
Pros and cons of AppSettings vs applicationSettings (.NET app.config / Web.config)
... you cannot safely assume your number that you wanted to configure there really is a number - someone could put a string into that setting..... you just access it as ConfigurationManager["(key)"] and then it's up to you to know what you're dealing with.
Also, over time, the <appSettings> can...
What are the big improvements between guava and apache equivalent libraries?
... me attempt to explain why.
Guava is more "modern"
Apache Commons is a really mature library, but it's also almost 10 years old, and targets Java 1.4. Guava was open sourced in 2007, targets Java 5, and thus Guava greatly benefits from the Java 5 features: generics, varargs, enums, and autoboxing....
Shortest distance between a point and a line segment
...ode, in C++. It presumes a class 2D-vector class vec2 {float x,y;}, essentially, with operators to add, subract, scale, etc, and a distance and dot product function (i.e. x1 x2 + y1 y2).
float minimum_distance(vec2 v, vec2 w, vec2 p) {
// Return minimum distance between line segment vw and point ...
How to check whether a pandas DataFrame is empty?
...[8]: len(df1.columns)
Out[8]: 0
In [9]: len(df2.columns)
Out[9]: 2
Critically, while the second dataframe df2 contains no data, it is not completely empty because it returns the amount of empty columns that persist.
Why it matters
Let's add a new column to these dataframes to understand the implic...