The formal parameter in the function is a structure pointer. There will be no error in how to write the argument

Question

This is a code I wrote today. The problem is as follows: The school is doing the project. Each teacher leads 5 students, a total of 3 teachers. The demand is as follows. Design the structure of students and teachers. In the structure of teachers, there are teachers' names and an array of 5 students as members Students' members have names and test scores. Create an array to store 3 teachers, and assign values to each teacher and students through functions Finally, print out the teacher data and the student data brought by the teacher., When I replace value delivery with address delivery, the error code is as follows:

#include<iostream>;
using namespace std;

#include<string>;


#include<ctime>;

struct Student {
    string name;
    int score;

};
struct Teacher {
    string name;
    struct Student sArray[5];
};

void printTeacher(struct Teacher tArray[], int len) {
    for (int i = 0; i < len; i++) {
        cout << "老师的姓名为" << tArray[i].name << endl;
        for (int j = 0; j < 5; j++) {
            cout << "\t学生的姓名为：" << tArray[i].sArray[j].name << " 学生的成绩为：" << tArray[i].sArray[j].score << endl;
        }
    }
}

void allocateSpace(struct Teacher * tArray[], int * len) {
    string nameseed = "ABCDE";
    string tname = "教师";
    string sname = "教师";
    for (int i = 0; i < * len; i++) {
        tArray[i] -> name = tname + nameseed[i];
        for (int j = 0; j < 5; j++) {
            tArray[i] -> sArray[j].name = sname + nameseed[j];
            tArray[i] -> sArray[j].score = rand() % 61 + 40;
        }
    }
}
int main() {
    srand((unsigned int) time(NULL)); //随机数种子 头文件 #include <ctime>
    struct Teacher tArray[3];
    int len = sizeof(tArray) / sizeof(tArray[0]);
    cout << tArray << endl;

    allocateSpace(tArray, & len);
    printTeacher(tArray, len);

    system("pause");
    return 0;
}

allocateSpace(tArray, &len); Here I am prompted that arguments and formal parameters are incompatible. Why and how?

Answer 1

The problem is that &tArray is a pointer to an array of 3 Teacher elements, i.e. a Teacher (*)[3] while your parameter is of type Teacher**. You may try this:

void allocateSpace(struct Teacher* tArray, int len) {
//                                         ^ no need for len to be a pointer
    string nameseed = "ABCDE";
    string tname = "??";
    string sname = "??";
    for (int i = 0; i <  len; i++) {
        tArray[i]. name = tname + nameseed[i];
        for (int j = 0; j < 5; j++) {
            tArray[i]. sArray[j].name = sname + nameseed[j];
            tArray[i]. sArray[j].score = rand() % 61 + 40;
        }
    }
}

// ...

// Here, tArray automatically decays to a pointer to its first
// element, i.e. to &tArray[0]:
allocateSpace(tArray, len);

Answer 2

You take the array by pointer, same as the length parameter so you have to also pass it the same way.

allocateSpace(&tArray, &len);
              ^pointer to array