stl string overloaded operators

This is a discussion on stl string overloaded operators within the C++ Programming forums, part of the General Programming Boards category; Hey, I don't typically use C++, I'm more of a C guy, but when using stl strings (std::string), as far ...

  1. #1
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    stl string overloaded operators

    Hey,

    I don't typically use C++, I'm more of a C guy, but when using stl strings (std::string), as far as the == operator goes.

    I go here for all my references for C++ and C.
    cplusplus.com - The C++ Resources Network

    I'm sure many others do, too. But it doesn't list == as an overloaded operator, with the semantics of .compare(). Though == works, apparently.

    Did cplusplus.com just forget it or something?? Is it not officially part of the STL spec? What gives?

    EDIT:
    Forgot to say, thanks in advance.

    Also, I know there's others like gotapi.com and cppreference.com - I just typically used cplusplus.com and was wondering if there was a particular (obvious) reason why it wasn't there..
    Last edited by Syndacate; 12-11-2010 at 01:03 PM.

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    operator == is not a member of the std::string class, if that's what you mean. It's just a free function.

    (EDIT: And it doesn't have the semantics of .compare() either -- operator== always returns true/false, while .compare() returns negative/0/positive like strcmp.)

  3. #3
    Registered User NeonBlack's Avatar
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    As tabstop mentioned, it (they, actually) are global operators, not members. The reference is here:
    comparison operators - C++ Reference
    I copied it from the last program in which I passed a parameter, which would have been pre-1989 I guess. - esbo

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    I get that they're not member functions, and yeah, I see the difference between that and compare, but are you trying to say that they're not overloaded for the string class? If so, how do they end up working for std::strings?

  5. #5
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by Syndacate
    I get that they're not member functions, and yeah, I see the difference between that and compare, but are you trying to say that they're not overloaded for the string class? If so, how do they end up working for std::strings?
    They are overloaded for the std::string class as non-member functions. One possible reason is so that there can be an overload of operator== for std::string which takes a const char* on the left hand side. This would not be possible with a member function.

    That said, there are many other member functions of std::string that could have been non-member non-friend functions. Read GotW #84: Monoliths Unstrung.
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