C - 初始化结构数组

Question

我在初始化结构数组时遇到问题。我不确定我是否做对了，因为我得到“从不兼容的指针类型初始化”和“从不兼容的指针类型赋值”。我在收到这些警告的代码中添加了代码，当我尝试从结构中打印数据时，我得到的只是垃圾，例如@@###

typedef struct
{
    char* firstName;
    char* lastName;
    int day;
    int month;
    int year;

}student;

//初始化数组

    student** students = malloc(sizeof(student));
    int x;
    for(x = 0; x < numStudents; x++)
    {
        //here I get: "assignment from incompatible pointer type" 
        students[x] = (struct student*)malloc(sizeof(student));
    }

    int arrayIndex = 0;

//添加结构

 //create student struct
        //here I get: "initialization from incompatible pointer type"
        student* newStudent = {"john", "smith", 1, 12, 1983};

        //add it to the array
        students[arrayIndex] = newStudent;
        arrayIndex++;

Answer 1

这是不正确的:

student** students = malloc(sizeof(student));

你不需要**。你想要一个 * 和足够的空间来容纳你需要的学生数量

student *students = malloc(numStudents * sizeof *students); // or sizeof (student)
for (x = 0; x < numStudents; x++)
{
    students[x].firstName = "John"; /* or malloc and strcpy */
    students[x].lastName = "Smith"; /* or malloc and strcpy */
    students[x].day = 1;
    students[x].month = 12;
    students[x].year = 1983;
}

如果您仍想使用“//add struct”部分中的代码，则需要更改以下行:

student* newStudent = {"john", "smith", 1, 12, 1983};

到

student newStudent = {"john", "smith", 1, 12, 1983};

您收到“从不兼容的指针类型进行初始化”，因为您试图使用类型为 student 的对象初始化指向 student 的指针。