释放动态结构数组的内存

Question

又是我:D

我有以下结构：

typedef struct
{
    int day, month, year;
}date;

typedef struct
{
    char name[15];
    date birth;
    int courses;
    int *grades;
}student;

这就是我为每个数组分配内存的方式：

printf("What is the number of students?\n");
    scanf("%d", &size); //asking for size from user and creating 'size' number of structs
    for (i = 0; i < size; i++) {
        pData[i] = malloc(sizeof(student) * size);
    }
    ........ //initializing char and birth
    for (i = 0; i < size; i++) {
        printf("\nPlease enter number of courses of student #%d:\n", i+1);
        scanf("%d", &pData[i]->courses); //allocating memory for array of grades for each student (i)
        pData[i]->grades = (int*)malloc(sizeof(int)*pData[i]->courses);
    }
    for (j = 0; j < size; j++) {
        for (i = 0; i < pData[j]->courses; i++) {
            printf("\nPlease enter grades of student #%d in course #%d\n", j+1, i+1);
            scanf("%d", &pData[j]->grades[i]);
        } //entering grades of each student

现在我无法释放内存...我尝试了很多方法，但程序每次都以错误结束..

我试过这个方法：

for (i = 0; i < size; i++) {
        free(pData[i].grades);
    }
    free(pData);
    pData = NULL;

但我仍然遇到错误...

编辑： 这就是我在 veriable pData 上声明的方式：

student* pData = NULL;

这就是初始化数组的函数:

int initialize(student**);

这就是我将 pData 发送到函数的方式：

size = initialize(&pData); //the function is suppose to return the size of the array.

Answer 1

您没有正确地为 pData 分配 space。您这样做一次并将其分配给 *pData，而不是 pData[i]。您有一个指向指针的指针，而不是指针数组。

printf("What is the number of students?\n");
scanf("%d", &size); //asking for size from user and creating 'size' number of structs
*pData = malloc(sizeof(student) * size);

然后你需要在读取数据时正确引用它。

for (i = 0; i < size; i++) {
    printf("\nPlease enter number of courses of student #%d:\n", i+1);
    scanf("%d", &(*pData)[i].courses); //allocating memory for array of grades for each student (i)
    (*pData)[i].grades = (int*)malloc(sizeof(int)*(*pData)[i].courses);
}
for (j = 0; j < size; j++) {
    for (i = 0; i < (*pData)[j].courses; i++) {
        printf("\nPlease enter grades of student #%d in course #%d\n", j+1, i+1);
        scanf("%d", &(*pData)[j].grades[i]);
    } 
}

编辑：

为了进一步说明pData的语法用法，这里是相关表达式各部分的数据类型。

         pData:   student **
        *pData:   student *
   (*pData)[i]:   student

释放动态结构数组的内存

Freeing memory of dynamic struct array

c

struct

dynamic-memory-allocation