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What is the role of "&" and "*" on operator overloading?


What is the role of "&" and "*" on operator overloading?

By : DeQuan Lynch
Date : November 22 2020, 02:42 PM
hope this fix your issue You want to operate on objects, not their copies, so this is why here are ampersands '&'. Const keyword indicates that You will not modify their values. The asterisk '*' is dereferencing a pointer to the newly created object, which is in this case leads to a memory leak as YSC said before. It is not allowed to create a new object and then do not store it in any container/pointer. You are responsible for their lifetime.
code :


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If Java has no operator overloading how is "string1" + "string2" possible?

If Java has no operator overloading how is "string1" + "string2" possible?


By : Leonardo Rebolledo
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , According to JavaDoc
"no match" and "cannot bind lvalue" errors while overloading `operator<<` with `std::wostream`

"no match" and "cannot bind lvalue" errors while overloading `operator<<` with `std::wostream`


By : Clayton
Date : March 29 2020, 07:55 AM
With these it helps I've got an error while overloading std::wostream::operator<<() for std::string. Here is the minimal test case illustrating my problem: , This is a bad idea:
code :
inline std::wostream &operator<<(std::wostream &os, const std::string &)
inline std::wostream &operator<<(std::wostream &os, const notstd::string &)
{
  return os;
}
#include <iostream>
#include <sstream>

namespace notstd {
  struct string {};
}

inline void operator<<(std::wostream &os, const notstd::string &){ return; }

class FakeOstream{};

namespace mynamespace {

  class UnusedClass1 {
    friend inline void operator<<(FakeOstream &out, const UnusedClass1 &) { return; }
  };

  class UnusedClass2 {
      // comment this line out and the code compiles:
    friend inline void operator<<(FakeOstream &out, const UnusedClass2 &) { return; }
  };

  void test() {
    auto mystring = notstd::string{};
    std::wostringstream s;
    s << mystring; // The errors occur here
  }

} // namespace mynamespace

int main(){}
Operator Overloading: How to add and compare data of two class "Integer" and "Fraction"

Operator Overloading: How to add and compare data of two class "Integer" and "Fraction"


By : Epigos
Date : March 29 2020, 07:55 AM
Any of those help For your first question, the solution is to not use member function overloads, but to create a non-member function overload, e.g.
code :
Fraction operator+(Integer const& integer, Fraction const& fraction)
{
    // Logic to add the integer and fraction here
    // Perhaps something like...
    Fraction f(integer.getValue(), 1);  // Create fraction
    return f + fraction;
}
randomly seeing 'Stub found while resolving method "???" overloading """" in package "

randomly seeing 'Stub found while resolving method "???" overloading """" in package "


By : Jota Teles
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further A suggested fix by a person who choices to remain anonymous (which was not enough for us in our perl 5.16.3)
We ended up switching to perl 5.26 and the problem is gone. (We were told "You are very unlikely to: 5.18 overhauled a lot of the overload internals.")
code :
diff --git a/lib/SQL/Abstract.pm b/lib/SQL/Abstract.pm
index 264b0b1..b4d8fb4 100644
--- a/lib/SQL/Abstract.pm
+++ b/lib/SQL/Abstract.pm
@@ -104,7 +104,11 @@ sub is_plain_value ($) {
         # "%s"> and the source of overload::mycan())
         #
         # either has stringification which DBI SHOULD prefer out of the box
-        grep { *{ (qq[${_}::(""]) }{CODE} } @{ $_[2] = mro::get_linear_isa( $_[1] ) }
+        grep {
+          *{ (qq[${_}::()]) }{CODE}
+            and
+          *{ (qq[${_}::(""]) }{CODE}
+        } @{ $_[2] = mro::get_linear_isa( $_[1] ) }
           or
         # has nummification or boolification, AND fallback is *not* disabled
         (
perl -e '

    use warnings;
    use strict;

    require Scalar::Util;

    {
      package Some::Overload;
      use overload
        q{""}       => "named_stringifier",
        fallback => 1,
      ;

      sub named_stringifier { $_[0] . "" }
    }

    {
      package Some::Subclass;
      use base "Some::Overload";
    }


    my $thing = bless {}, "Some::Subclass"; 


    {
      no strict "refs";
      grep { *{ (qq[${_}::(""]) }{CODE} } qw( Some::Subclass Some::Overload );
    }


    for (1, 2) {


      # simulates runtime require of some *UNRELATED* class
      eval sprintf <<EOS, $_;
      {
        package Some::UnrelatedThing%s;
        use overload
          q{""} => sub { \$_[0] . "" },
          fallback => 1,
        ;
      }
EOS

      my $some_object = bless {}, "Some::Subclass";
    }

    warn "got here, all is well\n";
    exit 0;
'
Having issues overloading "+,-,*" operators for vectors- "no match for operator..."

Having issues overloading "+,-,*" operators for vectors- "no match for operator..."


By : Dash
Date : March 29 2020, 07:55 AM
Hope this helps Your code doesn't compile because friend declarations only make the name available to argument-dependent lookup.
Since the arguments are in std, then only std is searched for operators. Your function is not in std so it is not found.
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