newb c++ code question

dragoon linux · 12-24-2003, 10:55 AM

Yes..... in the book I'm using to learn c++ I have this code that shows about random numbers:

#include <iostream>
#include <stdlib.h>
#include <time.h>

using namespace std;

int main()
{
time_t seconds;

time(&seconds);
srand((unsigned int) seconds);
cout << rand() << endl;
cout << rand() << endl;
cout << rand() << endl;
return 0;
}

Now I'm wondering, because it doesnt tell me, why the & has to be right before the seconds in : time(&seconds)...... like what is it there for and what does it do? thank you for any help...

h/w · 12-24-2003, 11:31 AM

its taking the argument which is a pointer, hence you pass it the address.

MartinN · 12-24-2003, 11:39 AM

time() takes an argument of type time_t * (pointer to time_t). The &-operator is called the address-operator, it gives the address of (pointer to) a variable.

This code is equivalent to your code (but less elegant):

Code:

#include <iostream>
#include <stdlib.h>
#include <time.h>

using namespace std;

int main()
{
  time_t *seconds = new time_t;

  time(seconds);
  srand((unsigned int) *seconds);
  cout << rand() << endl;
  cout << rand() << endl;
  cout << rand() << endl;

  delete seconds;

  return 0;
}

Regards
Martin

vinay_s_s · 12-24-2003, 12:05 PM

& is the address of operator. U better learn basics rather than going directly to tyme and other things. U seem to lack the basics.

Better learn C or buy a book which has basics of C/C++ and then read it!!!

dragoon linux · 12-24-2003, 12:11 PM

well I'm using a book my friend took from the comp lab at school O.o guess it's better to save it for later, anyone know any online books or such that can help/are good?

nibbler · 12-25-2003, 04:10 AM

http://www.bxteam.org/knjige.php
Teach yourself C/C++ in 21 days and Thinking in C++

FriedMalt · 12-26-2003, 09:23 AM

Quote:

Originally posted by nibbler
http://www.bxteam.org/knjige.php
Teach yourself C/C++ in 21 days and Thinking in C++

...I could kiss you for that link even though I wasn't the one asking for it, but I'll hold myself back. Thanks.

laceupboots · 12-26-2003, 11:15 PM

I liked this link too.

arrruken · 12-29-2003, 02:27 AM

Ive gotten alot of use out of www.cprogramming.com. I use a book too, but its nice to have explanations on a webpage i switch back and forth from when im programming.

laceupboots · 12-29-2003, 12:55 PM

Thanks arrruken, thats a great site too. I found some good compilers at this site. http://gcc.gnu.org/