What is the differnece between long and int?

[forumuser]

What is the differnece between long and int?

[matsp]

Sometimes long is bigger than int - are you doing a test or something?

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Mats

[cpjust]

long is always 4 bytes.
int is 2 bytes on 16-bit systems, 4-bytes on 32-bit systems, and I'm guessing it's 8 bytes on 64-bit systems.

[matsp]

long is always 4 bytes.
int is 2 bytes on 16-bit systems, 4-bytes on 32-bit systems, and I'm guessing it's 8 bytes on 64-bit systems.

There's no guarantee that Long is any particular size. It should be at least as long as an int. Most 64-bit systems have 64-bit longs and 32-bit ints, for example. long that is shorter than int is not allowed by the C standard.

--
Mats

[Salem]

The C standard specifies what the minimum requirements are for each data type.
Your compiler's limits.h file tells you what you've really got in terms of data type ranges.

[forumuser]

inser

int p=10;
int p;
int main()
{
 printf("%d",p)
 getch();
  return 0;
}
inser

The output is 10. Actually p is declared twice in a file. Hence, it should give compile time error. Then, why we get the output 10?

[Elysia]

What compiler?

[Prelude]

>Hence, it should give compile time error.
What makes you think that? C allows an object to be declared multiple times, and one of those declarations will be used as a definition. So in the end, there's really only one object. If you try to initialize more than one of the declarations, that constitutes a multiple definition, and you would get an error, but the following is perfectly legal C:

#include <stdio.h>

int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;

int main ( void )
{
  x = 12345;

  printf ( "%d\n", x );

  return 0;
}

So is this:

#include <stdio.h>

int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x = 12345; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;
int x; int x; int x;

int main ( void )
{
  printf ( "%d\n", x );

  return 0;
}

But this is not:

#include <stdio.h>

int x = 12345;
int x = 12345;

int main ( void )
{
  printf ( "%d\n", x );

  return 0;
}

There's no benign redefinition rule, so even if the initialization values are identical, it's still seen as multiple definitions. Only the third example will give you an error.

[cpjust]

Why would you exhume a 4 month old thread to ask a different question?

[matsp]

I think cpjust has a point - could one of the moderators dig out the other thread with exactly the same question, and perhaps merge the content of this thread to here.

--
Mats