How to put in a variable the result of an external pipe?

Question

This is my code (is a working in progress to calculate in GB the size of disk in a system)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main ()
{
char line[128];
 FILE* file = popen("/usr/sbin/prtvtoc /dev/rdsk/c0b0t2d0s0 |/usr/local/bin/grep 'slice 0' -A 2|grep length|cut -d : -f 3|cut -d '(' -f 1|cut -c 2-1000", "w");
  printf("The size in 512b blocks of the disk /dev/rdsk/c0b0t2d0s0del is %s \n",file);
  pclose(file);
  return 0;
  }

The output is very bad

The size in 512b blocks of the disk /dev/rdsk/c0b0t2d0s0del is
41929587 

I want

The size in 512b blocks of the disk /dev/rdsk/c0b0t2d0s0del is 41929587

My idea is to store in a variable the output of popen pipe, but I don't know how to do: is possible?

EDIT1:

I have tried this line

  printf("The size in 512b blocks of the disk /dev/rdsk/c0b0t2d0s0del is %d \n",*file);

but return 0