Question

WAP to check that system is 32 bit or 64 bit ?

Answer 1

int main()
{
    int *ptr;
    if (sizeof(ptr) < 8)
        printf("\nThis is 32 Machine \n");
    else
        printf("\nThis is 64 Machine \n");
}

Answer 2

1) Using Program
use the pointer size i.e.

sizeof (void *) * CHAR_BIT

to know the size of the machine in C program.

2) To know if PC/Laptop is 64/32bit
http://queryhome.com/11526/32-bit-vs-64-bit-how-to-check-my-pc-have-64-bit-cpu

3) On solaris, use
isainfo -b