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“using namespace” in c++ headers
In all our c++ courses, all the teachers always put using namespace std; right after the #include s in their .h files. This seems to me to be dangerous since then by including that header in another program I will get the namespace imported into my program, maybe without realizing, intending or...
What techniques can be used to speed up C++ compilation times?
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Take a look at the Pimpl idiom here, and here, also known as an opaque pointer or handle classes. Not only does it speed up compilation, it also increases exception safety when combined with a non-throwing swap function. The Pimpl idiom lets you reduce the dependencies between headers and reduces ...
What is java interface equivalent in Ruby?
Can we expose interfaces in Ruby like we do in java and enforce the Ruby modules or classes to implement the methods defined by interface.
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Finding a substring within a list in Python [duplicate]
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print [s for s in list if sub in s]
If you want them separated by newlines:
print "\n".join(s for s in list if sub in s)
Full example, with case insensitivity:
mylist = ['abc123', 'def456', 'ghi789', 'ABC987', 'aBc654']
s...
How can I get the version defined in setup.py (setuptools) in my package?
How could I get the version defined in setup.py from my package (for --version , or other purposes)?
16 Answers
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How to find third or nth maximum salary from salary table?
How to find third or nth maximum salary from salary table(EmpID,EmpName,EmpSalary) in Optimized way?
54 Answers
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SQL - using alias in Group By
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SQL is implemented as if a query was executed in the following order:
FROM clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
ORDER BY clause
For most relational database systems, this order explains which names (columns or aliases) are valid because the...
What exactly does += do in python?
I need to know what += does in python. It's that simple. I also would appreciate links to definitions of other short hand tools in python.
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Getting a list of values from a list of dicts
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Assuming every dict has a value key, you can write (assuming your list is named l)
[d['value'] for d in l]
If value might be missing, you can use
[d['value'] for d in l if 'value' in d]
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Constants in Objective-C
I'm developing a Cocoa application, and I'm using constant NSString s as ways to store key names for my preferences.
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