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Covariance and contravariance real world example
I'm having a little trouble understanding how I would use covariance and contravariance in the real world.
9 Answers
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How do you allow spaces to be entered using scanf?
...n).
Remember than scanf stands for "scan formatted" and there's precious little less formatted than user-entered data. It's ideal if you have total control of the input data format but generally unsuitable for user input.
Use fgets() (which has buffer overflow protection) to get your input into a ...
How to skip “Loose Object” popup when running 'git gui'
When I run 'git gui' I get a popup that says
4 Answers
4
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Naming conventions: “State” versus “Status” [closed]
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It depends on the context
State generally refers to the entire state of an entity - all its values and relationships at a particular point in time (usually, current)
Status is more of a time-point, say, where something is a...
`levels
...are good, but they are missing an important point. Let me try and describe it.
R is a functional language and does not like to mutate its objects. But it does allow assignment statements, using replacement functions:
levels(x) <- y
is equivalent to
x <- `levels<-`(x, y)
The trick is,...
How do I use a custom deleter with a std::unique_ptr member?
I have a class with a unique_ptr member.
6 Answers
6
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Reverse a string in Python
...gt;> 'hello world'[::-1]
'dlrow olleh'
This is extended slice syntax. It works by doing [begin:end:step] - by leaving begin and end off and specifying a step of -1, it reverses a string.
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Why does Java have transient fields?
...ike to a file) process.
From the Java Language Specification, Java SE 7 Edition, Section 8.3.1.3. transient Fields:
Variables may be marked transient to
indicate that they are not part of the
persistent state of an object.
For example, you may have fields that are derived from other field...
Most efficient method to groupby on an array of objects
...follow
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edited Mar 26 at 21:11
answered Jan 20 '16 at 2:02
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How to get ALL child controls of a Windows Forms form of a specific type (Button/Textbox)?
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Here's another option for you. I tested it by creating a sample application, I then put a GroupBox and a GroupBox inside the initial GroupBox. Inside the nested GroupBox I put 3 TextBox controls and a button. This is the code I used (even includes the recursion you...