Intro - Warning: BBBOORRRIINNGGG!!!!!

[wysota]

I didn't say I didn't like it I used to draw the alphabet using the turtle BASIC was my first language, though... I have been learning it more than 15 years ago on my ATARI 65XE box.

10 PRINT "Witek"
20 GOTO 10

10 PRINT "Witek"
20 GOTO 10

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[katrina]

I have actually never used logo at all...
I did load up KTurtle one day but it looked too complicated so I didn't mess with it much lol

const QString &signature = new QString("Katrina");

[wysota]

const QString &signature = new QString("Katrina");

Wow, two errors on one line! "new QString" returns QString* and not QString and you can't assign a newly created object to a reference -- a reference is just a "handler" for already existing objects. But besides that -- nice

[jacek]

you can't assign a newly created object to a reference

#include <iostream>
 
class Test {
   public:
      Test() {}
      int foo() const { return 1; }
};
 
int main()
{
   const Test& t = Test();
   std::cout << t.foo() << std::endl;
   return 0;
}

#include <iostream>

class Test {
   public:
      Test() {}
      int foo() const { return 1; }
};

int main()
{
   const Test& t = Test();
   std::cout << t.foo() << std::endl;
   return 0;
}

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[wysota]

#include <iostream>
 
class Test {
   public:
      Test() {}
      int foo() const { return 1; }
};
 
int main()
{
   const Test& t = Test();
   std::cout << t.foo() << std::endl;
   return 0;
}

#include <iostream>

class Test {
   public:
      Test() {}
      int foo() const { return 1; }
};

int main()
{
   const Test& t = Test();
   std::cout << t.foo() << std::endl;
   return 0;
}

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Are you sure this is correct? You hold a reference to a temporary object here. The fact that it works in this case doesn't mean this is a correct statement.

What if you store the reference to that object as a member of some class?

Will compiler optimisations not affect the correctness of the above statement?

[jacek]

Are you sure this is correct? You hold a reference to a temporary object here.

The secret lies in the "const" keyword.

[bood]

The secret lies in the "const" keyword.

yep, agree
And it's pretty useful.

void foo(const string & s); //no 'const' whill lead to error
foo("abc");

void foo(const string & s); //no 'const' whill lead to error
foo("abc");

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[wysota]

yep, agree
And it's pretty useful.

void foo(const string & s); //no 'const' whill lead to error
foo("abc");

void foo(const string & s); //no 'const' whill lead to error
foo("abc");

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In this case this is only because there is a cast defined from const char* to const string.

[jacek]

In this case this is only because there is a cast defined from const char* to const string.

I wouldn't be so sure:

#include <iostream>
#include <string>
 
void foo( std::string& s )
{
   std::cerr << s << std::endl;
}
 
int main()
{
   foo( std::string( "aaa" ) );
   return 0;
}

#include <iostream>
#include <string>

void foo( std::string& s )
{
   std::cerr << s << std::endl;
}

int main()
{
   foo( std::string( "aaa" ) );
   return 0;
}

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$ g++ -Wall a.cpp
a.cpp: In function `int main()':
a.cpp:11: error: invalid initialization of non-const reference of type 'std::string&' from a temporary of type 'std::string'
a.cpp:5: error: in passing argument 1 of `void foo(std::string&)'

[katrina]

Wow, two errors on one line! "new QString" returns QString* and not QString and you can't assign a newly created object to a reference -- a reference is just a "handler" for already existing objects. But besides that -- nice

LOL Hey, I was trying to be funny, not syntactically correct! LOL

QShutTheHeckUp *;-) = new QShutTheHeckUp;

(JUST KIDDING!)
sorry couldn't help myself :-D

Katrina