c - Dynamic 2D array in typedef

Question

How do I get this to work? I am not sure how many invoices a customer will be assigned to and want to leave it dynamic. Please help.

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

typedef struct _cust{
    int id;
    int invoices[][2];
} cust;

cust account[] = {
    {1,{10,100}},
    {2,{{10,100},{20,200}}},
    {3,{{10,100},{20,200},{30,300}}}
};

int main(void) {
    printf("%d\n", account[0].invoices[0][0]);
    printf("%d\n", account[1].invoices[1][0]);
    printf("%d\n", account[2].invoices[2][0]);
    return 0;
    }

When I run this code I get following error ...

error: initialization of flexible array member in a nested context

If I give fill in a number something like this int invoices[3][2], the code runs fine.

Answer 1

指向具有两个元素的数组的指针如下所示：

int (*array)[2];

但您可能更容易使用typedef第一个：

typedef int pair[2];
.
.
pair * array;

你可以为这样的野兽分配一大块。如果您有一个 C99（或更高版本）兼容的编译器，这将类似于

array = malloc(sizeof(pair[n]));

Answer 2

您可以更改invoices为int** invoices，然后使用动态分配malloc()。您可以像这样分配二维数组：

int** theArray;
theArray = (int**) malloc(arraySizeX*sizeof(int*));
for (int i = 0; i < arraySizeX; i++)
   theArray[i] = (int*) malloc(arraySizeY*sizeof(int));