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I noticed on several places within various languages (C++, Java, Python...)usage of _variable naming. What does this indicate?

General Grievance
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ps-aux
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  • In C it was used to declare system / internal variables. And the C programmers learnt Java and introduced it there as well though it is against java naming convention. – Leos Literak Mar 20 '14 at 07:33
  • I suggest you specify a single language, or this may be multiple questions in one. – Ciro Santilli OurBigBook.com Mar 20 '14 at 07:33
  • For Python, possible duplicate of: http://stackoverflow.com/questions/1301346/the-meaning-of-a-single-and-a-double-underscore-before-an-object-name-in-python – Ciro Santilli OurBigBook.com Mar 20 '14 at 07:34
  • In C++ they are reserved keywords http://en.cppreference.com/w/cpp/keyword "begins with an underscore followed by an uppercase letter is always reserved to the implementation and should not be used as an identifier." – Chemistpp Mar 20 '14 at 07:34

2 Answers2

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in c or c++, _ is used start of variable name for some variable used in lib code.to prevent to same name found in your code and the lib. I python _ is used for result that wasn't assigned to a variable .

madan ram
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In Python:

_ = 1
(_-_) will now equal 0
PascalVKooten
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