使用malloc創建一個指向多個項目結構

Question

對於交流編程類，我被告知要創建的typedef以下結構，按照這個順序：

//STRUCTS 
struct time { 
    unsigned int hour; 
    unsigned int minute; 
    unsigned int second; 
};//end struct time 
struct date { 
    unsigned int month; 
    unsigned int day; 
    unsigned int year; 
};//end struct Date 
struct event { 
    char name[20]; 
    struct time* time; 
    struct date* date; 
};//end struct event 

//TYPEDEFS 
typedef struct time Time; 
typedef struct date Date; 
typedef struct event Event; 

從那裏，我應該問要創建的最大事件數量，然後分配一個具有足夠內存的指針用於許多事件。我的部分工作是：

Event *events; 

//Ask for max number of events and allocate memory 
printf("Number of events to add: "); 
scanf("%d", &numEvents); 
events = (Event*) malloc(sizeof(Event) * numEvents); 

但是，從那裏我不確定如何遍歷指針查看特定事件。我知道這不僅僅是一個數組，所以events [i]將不起作用。但除此之外，我迷路了。爲獲得一個事件我（打破）函數是：

void getEvent(Event *events, int index){ 
    //variables 
    char title[20]; 
    unsigned int day, month, year, hour, minute, second; 
    Event tempEvent; 


    //Ask for input 
    printf("Input title, date, and time.\n"); 
    if(index == 0) 
     printf("example -> title: dd/mm/yy hh:mm:ss\n"); 

    //Take input 
    scanf("%20[^:]: %u/%u/%u %u:%u:%u", title, &day, &month, &year, &hour, &minute, &second); 


    tempEvent = (Event) {*title, { hour, minute, second }, { month, day, year } }; 

    events[index] = tempEvent;  
} 

我知道，這是不對的，和我在測試段故障。

當我編譯，我得到這些警告（和有關類似事情有些重複）：

Lab4.c: In function ‘getEvent’: Lab4.c:82:2: warning: braces around scalar initializer 
tempEvent = (Event) {*title, { hour, minute, second }, { month, day, year } }; 
^ Lab4.c:82:2: note: (near initialization for ‘(anonymous).name[1]’) 

Lab4.c:82:39: warning: excess elements in scalar initializer 
tempEvent = (Event) {*title, { hour, minute, second }, { month, day, year } } 

Answer 1

編譯器告訴你，行82是一個爛攤子。

tempEvent = (Event) {*title, { hour, minute, second }, { month, day, year } }; 

特別地，event結構的第一構件是一個數組char name[20]，但在嘗試使用單個字符*title進行初始化。但更大的問題是time和date（在event結構中）是指針，並且您沒有爲這些指針分配任何內存。

一種解決辦法是分配內存，然後有scanf填充中的值，如下所示：

void getEvent(Event *events, int n) 
{ 
    // allocate memory 
    events[n].time = malloc(sizeof(Time)); 
    events[n].date = malloc(sizeof(Date)); 
    if (events[n].time == NULL || events[n].date == NULL) 
    { /* TODO: handle the error */ } 

    //Ask for input 
    printf("Input title, date, and time.\n"); 
    if (n == 0) 
     printf("example -> title: dd/mm/yy hh:mm:ss\n"); 

    //Take input 
    int count = scanf("%20[^:]:%u/%u/%u%u:%u:%u", events[n].name, 
         &events[n].date->day, &events[n].date->month, &events[n].date->year, 
         &events[n].time->hour, &events[n].time->minute, &events[n].time->second); 
    if (count != 7) 
    { /* TODO: handle the error */ } 
}