What is a functio nthat produces itself called? I can;t recall for the
life of me...
Thanks
Cheers!
--
Vig
10  1396 
Vig wrote:
What is a functio nthat produces itself called? I can;t recall for the
life of me...
Thanks
Cheers!
--
Vig
function that produces itself? I haven't seen such kind of function.
-- Murali Krishna
Vig wrote:
What is a functio nthat produces itself called? I can;t recall for the
life of me...
Not exactly a C++ question, but ...
If you mean program rather than function then are you thinking of this? http://en.wikipedia.org/wiki/Quine
Gavin Deane
Gavin Deane wrote:
Vig wrote:
>What is a functio nthat produces itself called? I can;t recall for the
life of me...
Not exactly a C++ question, but ...
If you mean program rather than function then are you thinking of this?
http://en.wikipedia.org/wiki/Quine
Gavin Deane
YESS!!!
Life saver!
Cheers!
--
Vig
Vig posted:
What is a functio nthat produces itself called? I can;t recall for the
life of me...
Thanks
Cheers!
Asexual?
--
Frederick Gotham
Vig wrote:
Gavin Deane wrote:
Vig wrote:
What is a functio nthat produces itself called? I can;t recall for the
life of me...
Not exactly a C++ question, but ...
If you mean program rather than function then are you thinking of this?
http://en.wikipedia.org/wiki/Quine
Gavin Deane
YESS!!!
Life saver!
Cheers!
--
Vig
Ah.. I thought there is no such kind of thing in the world. Sorry for
that.
There are many helping hands in this group like Gavin Deane.
-- Murali Krishna
"Murali Krishna" <pm*********@gm ail.comwrote in message
news:11******** **************@ 35g2000cwc.goog legroups.com...
>
Vig wrote:
>What is a functio nthat produces itself called? I can;t recall for the
life of me...
Thanks
Cheers!
--
Vig
function that produces itself? I haven't seen such kind of function.
The question has already been answered, but I had to try out of curiosity.
This program gives a memory violation trying to write to memory on the 2nd
call to FuncP. I was sure it wouldn't work, but had to see what would
happen anyway.
#include <string>
#include <iostream>
int TestFunction()
{
return 2;
}
typedef int (*Func)();
int main()
{
Func FuncP;
FuncP = TestFunction;
int x = FuncP();
std::cout << x << std::endl;
FuncP = (Func)malloc( 1000 );
memcpy( FuncP, TestFunction, 1000 );
x = 4;
x = FuncP(); // Crashes here
free(FuncP);
std::cout << x << std::endl;
std::string wait;
std::cin >wait;
}
Jim Langston wrote:
[..]
The question has already been answered, but I had to try out of
curiosity. This program gives a memory violation trying to write to
memory on the 2nd call to FuncP. I was sure it wouldn't work, but
had to see what would happen anyway.
#include <string>
#include <iostream>
int TestFunction()
{
return 2;
}
typedef int (*Func)();
int main()
{
Func FuncP;
FuncP = TestFunction;
int x = FuncP();
std::cout << x << std::endl;
FuncP = (Func)malloc( 1000 );
So, here 'FuncP' is a pointer to *data*. Even though you cast it to
a pointer to function, it doesn't really point to any function, does it?
memcpy( FuncP, TestFunction, 1000 );
Now, since 'TestFunction' is not a pointer to an object, the behaviour
of that code is undefined. But even if we assume that you're allowed
to read bytes from the memory location behind 'TestFunction', you're
storing those bytes into data memory.
>
x = 4;
x = FuncP(); // Crashes here
And here you're asking to treat the data as if it were *code*.
In modern OSes, you cannot execute data unless you have special
permissions or changed permissions (or properties) of the memory
where you want to create code. Of course it doesn't work.
>
free(FuncP);
std::cout << x << std::endl;
std::string wait;
std::cin >wait;
}
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
Jim Langston wrote:
The question has already been answered, but I had to try out of curiosity.
This program gives a memory violation trying to write to memory on the 2nd
call to FuncP. I was sure it wouldn't work, but had to see what would
happen anyway.
You need to know how to allocate memory with execute permission in your
operating system (if it allows that), and if the machine code of your
processor is relocatable, or if the compiler has some option to generate
relocatable code. A general portable way does not exists.
--
Salu2
"Jim Langston" <ta*******@rock etmail.comwrote in message
news:EC******** *******@fe04.lg a...
"Murali Krishna" <pm*********@gm ail.comwrote in message
news:11******** **************@ 35g2000cwc.goog legroups.com...
Vig wrote:
What is a functio nthat produces itself called? I can;t recall for the
life of me...
Thanks
Cheers!
--
Vig
function that produces itself? I haven't seen such kind of function.
The question has already been answered, but I had to try out of curiosity.
This program gives a memory violation trying to write to memory on the 2nd
call to FuncP. I was sure it wouldn't work, but had to see what would
happen anyway.
How about recursive function?
regards,
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