Using pointers to modify values stored in some other variables.
#include <stdio.h> int main(void) { long num1 = 0L; long num2 = 0L; long *pnum = NULL; pnum = &num1; // Get address of num1 *pnum = 2L; // Set num1 to 2 ++num2; // Increment num2 num2 += *pnum; // Add num1 to num2 pnum = &num2; // Get address of num2 ++*pnum; // Increment num2 indirectly printf("num1 = %ld num2 = %ld *pnum = %ld *pnum + num2 = %ld\n", num1, num2, *pnum, *pnum + num2);/*from w w w.java 2 s . c o m*/ return 0; }