c - 将指向结构数组的指针传递给 malloc 的函数

Question

我环顾四周，找到了有关如何使用指针表示法为二维数组正确分配内存的答案，并且我找到了如何将二维指针数组正确传递给函数的方法，但我似乎无法结合这两个步骤。

所以从逻辑上讲，我要做的是分配一个指向结构的指针数组。似乎失败的是尝试分配内存

到目前为止我的代码:

typedef struct {
int tax, savings;
float salary;
} employee;

int readRecordFile(char* filename, Record*** array);

int main(void) {

employee** array;
int size;
char* file = "money.csv";
size = readRecordFile(file, &array);

FILE* fptr;
fptr = fopen(file, "r");


//Read the file into the the array 
for (int i = 0; i < size; i++) {
    fscanf(fptr, "%d,%d,%f", array[i]->tax, array[i]->savings, array[i]->salary);
}
fclose(fptr);


for (int i = 0; i < size; i++) {
    printf("%d, %d, %f\n", array[i]->tax, array[i]->savings, array[i]->salary);
}
return 0;
}

int readRecordFile(char* filename, employee*** array) {
//Function to open the file, malloc and initialize 2d arrays

//Open the file
FILE* fileptr;
fileptr = fopen(filename, "r");
if (fileptr == NULL) {
    printf("Failed to open file");
    exit(-1);
}

//Read first line of file (the size) and store to an int
int n;
fscanf(fileptr, "%d", &n);

//Initial malloc for the array of pointers
**array = malloc(n * sizeof(employee*)); //This is the line that throws the exception

//Malloc for each pointer in the array of pointers
for (int i = 0; i < n; i++) {
    *(array+i) = malloc(sizeof(employee));
}


//Close the file and return the size of the file
fclose(fileptr);

return n;
}

我试过在函数中构建一个单独的结构指针，然后将常规指针设置为指向它

    //Initial malloc for the array of pointers
employee **tester = malloc(n * sizeof(employee*));

//Malloc for each pointer in the array of pointers
for (int i = 0; i < n; i++) {
    *(tester+i) = malloc(sizeof(employee));
}

array = tester;

这个方法貌似解决了malloc的问题，但是main打印数据失败了。

Answer 1

您正在正确分配结构的二维数组。

但您只是读取结构的一维数组。 (例如 array[i]->tax)

要读取结构的二维数组，您需要 2 个 for 循环

for (int i = 0; i < size; i++) {
    for (int j=0; j< size; j++) { // in your case you have a size*size array, 
        fscanf(fptr, "%d,%d,%f", array[i][j]->tax, array[i][j]->savings, array[i][j]->salary);
     }
}

您需要决定是需要一维数组还是二维数组。