Karel command question what is the :: operator ?

    Hi ,

    In Karel, i once in awhile will come across an language instruction that looks like this :: in the code. I cannot seem to find this anywhere in the karel manual and wondered if someone could please answer what it does.

    Here are some examples of its use. These snippets are from some modbus socket messaging code running on a RJ3ib controller.

    IF (debug > 1) THEN; WRITE('bc = ', bc::3::16, cr); ENDIF

    -- Read the Reference
    READ file_var(ref::2)

    -- Send Response!
    header[6] = 6
    WRITE file_var(header[1]::1, header[2]::1, header[3]::1, header[4]::1, header[5]::1, header[6]::1,
    header[7]::1, fc::1, ref::2, wc::2)

    IF (debug > 3) THEN
    WRITE('pr_value.x = ', pr_value.x::6::2 , cr)
    WRITE('pr_value.y = ', pr_value.y::6::2 , cr)
    WRITE('pr_value.z = ', pr_value.z::6::2 , cr)
    WRITE('pr_value.w = ', pr_value.w::6::2 , cr)
    WRITE('pr_value.p = ', pr_value.p::6::2 , cr)
    WRITE('pr_value.r = ', pr_value.r::6::2 , cr)
    ENDIF

    Thanks much -Eric

    Edited once, last by Chipprogr (June 11, 2017 at 8:22 PM).

    Found this online. Hope it helps.
    Also check this out: http://icarus.cs.weber.edu/~dab/cs1410/te…/operators.html

    :: is the scope resolution operator - used to qualify names. In this case it is used to separate the class AirlineTicket from the constructor AirlineTicket(), forming the qualified name AirlineTicket::AirlineTicket()

    You use this whenever you need to be explicit with regards to what you're referring to. Some samples:

    namespace foo {
    class bar;
    }
    class bar;
    using namespace foo;

    Now you have to use the scope resolution operator to refer to a specific bar.

    ::foo::bar is a fully qualified name.

    ::bar is another fully qualified name. (:: first means "global namespace")

    struct Base {
    void foo();
    };
    struct Derived : Base {
    void foo();
    void bar() {
    Derived::foo();
    Base::foo();
    }
    };

    This uses scope resolution to select specific versions of foo.

    Edited once, last by mortoch (June 12, 2017 at 3:31 AM).

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