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do..end vs curly braces for blocks in Ruby
...-line blocks and curly braces for single line blocks, but there is also a difference between the two that can be illustrated with this example:
puts [1,2,3].map{ |k| k+1 }
2
3
4
=> nil
puts [1,2,3].map do |k| k+1; end
#<Enumerator:0x0000010a06d140>
=> nil
This means that {} has a high...
Test if string is a number in Ruby on Rails
...is_number? Method.
Create a helper method:
def is_number? string
true if Float(string) rescue false
end
And then call it like this:
my_string = '12.34'
is_number?( my_string )
# => true
Extend String Class.
If you want to be able to call is_number? directly on the string instead of pa...
Check if a string contains one of 10 characters
I'm using C# and I want to check if a string contains one of ten characters, *, &, # etc etc.
6 Answers
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Fragment onResume() & onPause() is not called on backstack
...They are tightly coupled to the Activity.
Read the Handling the Fragment Lifecycle section of this article.
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close vs shutdown socket?
In C, I understood that if we close a socket, it means the socket will be destroyed and can be re-used later.
9 Answers
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How does Dijkstra's Algorithm and A-Star compare?
...f each node is calculated by f(x)=g(x)+h(x)
A* search only expands a node if it seems promising. It only focuses to reach the goal node from the current node, not to reach every other nodes. It is optimal, if the heuristic function is admissible.
So if your heuristic function is good to approximat...
How to get a variable value if variable name is stored as string?
How can I retrieve a bash variable value if I have the variable name as string?
7 Answers
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How to check if AlarmManager already has an alarm set?
When my app starts, I want it to check if a particular alarm (registered via AlarmManager) is already set and running. Results from google seem to indicate that there is no way to do this. Is this still correct? I need to do this check in order to advise the user before any action is taken to create...
How to detect if my shell script is running through a pipe?
How do I detect from within a shell script if its standard output is being sent to a terminal or if it's piped to another process?
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UIPanGestureRecognizer - Only vertical or horizontal
...omeView];
return fabs(velocity.y) > fabs(velocity.x);
}
And for Swift:
func gestureRecognizerShouldBegin(_ gestureRecognizer: UIPanGestureRecognizer) -> Bool {
let velocity = gestureRecognizer.velocity(in: someView)
return abs(velocity.x) > abs(velocity.y)
}
...