如何正确地为 C 中的结构数组分配内存？

Question

这是我第一次使用结构体，因为我对 C 还是比较陌生。当我尝试为 3 个结构体输入值时，程序崩溃了，但它对 1 和 2 工作正常。我想我实际上可能没有分配足够的记忆。这是为结构数组分配内存的正确方法吗？

#include <stdio.h>
#include <stdlib.h>

#define MIN_SIZE 0
#define MAX_SIZE 100
#define MAX_MONTH_STR 9

//Define a struct data type
typedef struct
{
    char* month;
    int day;
    int year;
}date;

//Method to allocate memory for a list of date structures
date* allocateStruct(int size)
{
    //Declaration of variables
    date *array;
    int i;

    //Allocate memory for rows (to store 'size' many pointers to 'date' struct data type)
    array = malloc(size*sizeof(date*));

    //For-loop to allocate memory for columns (to store 'size' many integers, and initialize them to zero)
    for (i=0; i<size; i++)
    {
        array[i].month = calloc(MAX_MONTH_STR,sizeof(char));
        array[i].day = calloc(1,sizeof(int));
        array[i].year = calloc(1,sizeof(int));
    }

    return array;
}

//Method to free memory allocated
//TO DO. . .

int main()
{
    //Declaration of variables
    int n;
    date* date_list;
    int i, j, k; //used in loops

    //Read input
    do
    {
        //printf("Enter number of dates you want to enter (between 1 and 10000):\n");
        scanf("%d", &n);
    }while(n<MIN_SIZE || n>MAX_SIZE);

    //ALLOCATE MEMORY
    date_list = allocateStruct(n);


    //For-loop to store values in 'date_list'
    for (i=0; i<n; i++)
    {
        //printf("Enter the date (month day year) in the following format: text number number");
        scanf("%s", date_list[i].month);
        scanf("%d", &date_list[i].day);
        scanf("%d", &date_list[i].year); //need & ?
    }

//--------> crashes here if 3 dates are input, ok for 1 and 2

    //Test print
    for (i=0; i<n; i++)
    {
        //printf("Enter the date (month day year) in the following format: text number number");
        printf("%s ", date_list[i].month);
        printf("%d ", date_list[i].day);
        printf("%d\n", date_list[i].year); //need & ?
    }

    return 0;
}

Answer 1

您正在尝试使用指向日期结构的指针大小而不是日期结构的实际大小分配数组。

更改date*为date：

array = malloc(size*sizeof(date));

此外，您不需要分配 day 和 year 变量，因为 malloc 会为您分配它们。

for (i=0; i<size; i++)
{
     array[i].month = calloc(MAX_MONTH_STR,sizeof(char));
     array[i].day = 0;
     array[i].year = 0;
}