分配功能指针

#include <stdio.h>

/* increment: take number, increment it by one, and return it */
int increment(int i)
{
    printf("increment %d by 1\n", i);
    return i + 1;
}

/* decrement: take number, decrement it by one, and return it */
int decrement(int i)
{
    printf("decrement %d by 1\n", i);
    return i - 1;
}

int main(void)
{
    int num = 0;          /* declare number to increment */
    int (*fp)(int);       /* declare a function pointer */

    fp = &increment;      /* set function pointer to increment function */
    num = (*fp)(num);     /* increment num */
    num = (*fp)(num);     /* increment num a second time */

    fp = &decrement;      /* set function pointer to decrement function */
    num = (*fp)(num);     /* decrement num */
    printf("num is now: %d\n", num);
    return 0;
}