Thread: Simple Memory Content Question

Because those arrays decay to pointers and pointers contain a memory address. You're printing the memory address.
If the memory address was not the same, it would be the same array or variable which would make no sense. Because you're creating two different arrays, and then copying the contents into each other.

So to sum it up: they have the same contents, but they are different arrays, so the memory address is different.
(You can't expect to take two mugs, one full of beer, then pour the beer into the other mug and place them at the exact same location [x, y, z]. It's impossible, and it's likewise impossible in the computer world [x, y, z being the memory address].)

Originally Posted by azzuwan

Shouldn't str1 and str2 have the same contents regardless what kind of representation I use for printing the values wether in string, hex or int form...? why does the two values differ in hex representations but not in string form?

The real issue here is that when you pass a string to printf() [or any other function for that matter], you actually just pass the location of the string. Inside printf, the different %letter combinations will then take the respective argument and do the relevant display operation.

In the case of %s, it does something like this:

Code:

   case 's':
    char *str = getnextargument();
    while(*str)  
    {
        putchar(*str);
        str++;
    }
    break;

in another place you'd find the %x code:

Code:

    case 'X':
       usecapitals = 1;
    case 'x':
       unsigned int val = getnextargument();
       char buffer[9];
       // Convert x to a string in buffer, using base 16.
       num2str(buffer, x, 16, usecapitals);
       puts(buffer);
       break;

The above code is heavily simplified, and both of these cases are probably 3-5x longer in a real printf implementation, mostly to handle width and right/left positioning.

But as you can perhaps figure out, getnextargument() is a generic function to pick up the next of the arguments, and printf itself DOESN'T know what the next argument represents in itself, it just sees the numeric value as a value that it prints in the form that you've asked for.

If you print a string as %X, it will show you the address of the string, not the string itself, as hex.

--
Mats

Just a thought, but if you want more features that are available in managed environment while still remaining close to the hardware, try C++, since it's an evolution of C.