二级指针

# include <stdio.h>
int main(void)
{
    int i = 10;
    int *p = &i;
    int **q = &p;
    printf("i = %d\n", i);
    printf("i = %d\n", *p);
    printf("i = %d\n", **q);
    return 0;
}

result1

函数指针

# include <stdio.h>
int Max(int, int);  //函数声明
int main(void)
{
    int(*p)(int, int);  //定义一个函数指针
    int a, b, c;
    p = Max;  //把函数Max赋给指针变量p, 使p指向Max函数
    printf("please enter a and b:");
    scanf("%d%d", &a, &b);
    c = (*p)(a, b);  //通过函数指针调用Max函数
    printf("a = %d\nb = %d\nmax = %d\n", a, b, c);
    return 0;
}
int Max(int x, int y)  //定义Max函数
{
    int z;
    if (x > y)
    {
        z = x;
    }
    else
    {
        z = y;
    }
    return z;
}

result2

数组和链表

访问数组

Event *event_cur = *(calendar->events+day-1);

访问链表

event_temp = event_cur->next;
while (event_temp != NULL) {
      if((*(calendar->comp_func))(event_temp, event)<0){
        event_cur = event_temp;
        event_temp = event_temp->next;
      }
      else{
        break;
      }
}
event_cur->next = event;
event->next = event_temp;   
/**************************************************/
event_temp = event_cur->next;
while (event_temp != NULL) {
        if(strcmp(event_temp->name,name) == 0){
          event_cur->next = event_temp->next;
          if(event_temp->info != NULL&&calendar->free_info_func != NULL){
            (*(calendar->free_info_func))(event_temp->info);
          }
          free(event_temp->name);
          free(event_temp);
          calendar->total_events -= 1;
          event_temp = event_cur->next;
        }
        else{
          event_cur = event_cur->next;
          event_temp = event_temp->next;
        }
}    

int add_event(Calendar *calendar, const char *name, int start_time, int duration_minutes, void *info, int day){
  Event *event;
  Event *event_cur = *(calendar->events+day-1);
  Event *event_temp = event_cur;

  if(calendar==NULL||name==NULL||start_time<0||start_time>2400||duration_minutes<=0||day<1||day>calendar->days){
    return FAILURE;
  }

  /*check event existing*/
  if(find_event(calendar, name,&event)==SUCCESS){
    return FAILURE;
  }

  event = (Event *)malloc(sizeof(Event));
  event->name = (char *)malloc(80*sizeof(char));
  strcpy(event->name, name);
  event->start_time = start_time;
  event->duration_minutes = duration_minutes;
  event->info = info;
  event->next = NULL;

  if(event == NULL||event->name ==NULL){
    return FAILURE;
  }

  /* insert event */
  if(event_cur==NULL){
    *(calendar->events+day-1) = event;
  }
  else if((*(calendar->comp_func))(event_cur, event)>0){
    *(calendar->events+day-1) = event;
    event->next = event_cur;
  }
  else{
    event_temp = event_cur->next;
    while (event_temp != NULL) {
      if((*(calendar->comp_func))(event_temp, event)<0){
        event_cur = event_temp;
        event_temp = event_temp->next;
      }
      else{
        break;
      }
    }

    event_cur->next = event;
    event->next = event_temp;
  }

  calendar->total_events += 1;
  return SUCCESS;

Makefile

CC = gcc
CFLAGS = -ansi -Wall -g -O0 -Wwrite-strings -Wshadow \
-pedantic-errors -fstack-protector-all
PROGS = public01 public02 public03 public04 public05 student_tests

.PHONY: all clean

all: $(PROGS)

clean:
    rm -f *.o $(PROGS) a.out

$(PROGS): calendar.o my_memory_checker_216.o
public01: public01.o
public02: public02.o
public03: public03.o
public04: public04.o
public05: public05.o
student_tests: student_tests.o

calendar.o: calendar.h event.h
my_memory_checker_216.o: my_memory_checker_216.h
public01.o: calendar.h my_memory_checker_216.h event.h
public02.o: calendar.h my_memory_checker_216.h event.h
public03.o: calendar.h my_memory_checker_216.h event.h
public04.o: calendar.h my_memory_checker_216.h event.h
public05.o: calendar.h my_memory_checker_216.h event.h
student_tests.o: calendar.h my_memory_checker_216.h event.h

sponsor:
    @echo "This exercise brought to you by pepsi"