string::size_type vs. int

This is a discussion on string::size_type vs. int within the C++ Programming forums, part of the General Programming Boards category; The C++ std::string class provides string::size_type as an integer datatype large enough to represent any possible string size. The maximum ...

  1. #1
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    string::size_type vs. int

    The C++ std::string class provides string::size_type as an integer datatype large enough to represent any possible string size.

    The maximum value of an int is 2,147,483,647.

    Meaning that if a line or page wont hold more than 2,147,483,647 characters
    - which in normal cases never do - then you dont have to bother declaring string::size_type, you can just declare an int, which is much more simple.

    Am i right or am i right?
    Compiler MSVC++ 2013 with Code::Blocks.

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    In theory, you don't have any knowledge about string::size_type, it could be a 16-bit integer, a 32-bit integer or a 64-bit integer [or a floating point variable for all you know].

    The value is most likely compatible with an int, but the CORRECT thing to do is to always use the string::size_type. That is guaranteed to ALWAYS work. [Just be aware that if you change the STL implementation that you use for a particular software setup, you WILL need to recompile ALL of your code, or bad things may happen - but that's true even if you don't use string::size_type].

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    Hmm i see. Thanks Matsp!
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    By the way, it's most likely an UNSIGNED integer, since it's very unlikely that the size of a string is negative.

    Mixing unsigned and signed variables will sometimes cause a problem [usually when you are outside the range of either type, e.g. large unsigned numbers become negative, or negative numbers become large positive when translated from one to the other].

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    Quote Originally Posted by matsp View Post
    In theory, you don't have any knowledge about string::size_type, it could be a 16-bit integer, a 32-bit integer or a 64-bit integer [or a floating point variable for all you know].
    It certainly won't be floating point. A size_type is guaranteed to be an unsigned integral type.

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    Quote Originally Posted by Ducky View Post
    The C++ std::string class provides string::size_type as an integer datatype large enough to represent any possible string size.

    The maximum value of an int is 2,147,483,647.

    Meaning that if a line or page wont hold more than 2,147,483,647 characters
    - which in normal cases never do - then you dont have to bother declaring string::size_type, you can just declare an int, which is much more simple.

    Am i right or am i right?
    Since you certainly won't have a negative number of characters, a signed number is kind of pointless since you're wasting half the range.

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