如何在没有指针的情况下存储变量的地址

Question

how can we store the address of the variable without using the pointer?

#include<stdio.h>
int main ()
{
    double sum;
    double x= &sum;

    printf("\n %lf",x);
}

Answer 1

By definition, a pointer is an object that stores the address of another. How can you store something without using the appropiate storage variable for that kind of data? There are no other objects to store addresses, so what do you suggest?

If you just want to print the address to stdout , just do the following:

    printf("%p\n", &sum);

The format specifier %p allows you to pass a pointer, and you can use &sum directly to pass the value of the address of sum .

Answer 2

You did it almost right. But you stored it in a double , the memory address of a variable can be 4 bytes, or 8 bytes, depending on the implementation. You should always cast to a wider type though. Right now, storing it in a double may cause loss of information.

You'll need to use a data type wide enough. You could use an unsigned long long , however for cross platform compatibility, I recommend using uint64_t from stdint.h instead. And also the accompanying inttypes.h .

#include<stdio.h>
#include<stdint.h>
#include<inttypes.h>

int main()
{
    double sum;
    uint64_t x = (uint64_t) &sum;

    printf("%" PRIx64 "\n", x);
}

This ensures that you use an unsigned 64 bit (8 byte) variable so you do not lose information.

Also print using the PRIx64 format specifier for getting output in 64 bit hexadecimal form.

Do note however, this is only good for printing the address, and address only. This really does not serve any practical purpose.