The following sample program, foo.c, directly illustrates the effect of the LP64 data model in contrast to the ILP32 data models. The same program can be compiled as either a 32-bit program or a 64-bit program.
#include <stdio.h>
int
main(int argc, char *argv[])
{
(void) printf("char is \t\t%lu bytes\n", sizeof (char));
(void) printf("short is \t%lu bytes\n", sizeof (short));
(void) printf("int is \t\t%lu bytes\n", sizeof (int));
(void) printf("long is \t\t%lu bytes\n", sizeof (long));
(void) printf("long long is \t\t%lu bytes\n", sizeof (long long));
(void) printf("pointer is \t%lu bytes\n", sizeof (void *));
return (0);
}
The result of 32-bit compilation is:
$ cc -m32 -O -o foo32 foo.c $ foo32 char is 1 bytes short is 2 bytes int is 4 bytes long is 4 bytes long long is 8 bytes pointer is 4 bytes
The result of 64-bit compilation is:
$ cc -m64 -O -o foo64 foo.c $ foo64 char is 1 bytes short is 2 bytes int is 4 bytes long is 8 bytes long long is 8 bytes pointer is 8 bytes