#include <stdio.h> int main() { double a[20]; double* ptrDouble = a; double sum = 0; int i = 0; for (i = 0; i < 20; i++) *(ptrDouble + i) = 3.2 * i + 1.5; ptrDouble = a + 10; for (i = 0; i < 10; i++) sum += *(ptrDouble + i); for (i = -10; i < 10; i++) printf("%.2lf ", *(ptrDouble + i)); printf("\nsum=%.2lf\n", sum);