C 中的函数和内存：在堆上分配内存

Question

struct Country{ 
int *GDPBillions;
int *GDPPerCapita; 
int *NetWealthTrillions; }; 
struct Country USA;
struct Country* usa_pointer = (struct Country*)malloc(sizeof(struct Country));
usa_pointer->GDPBillions = (int*)malloc(sizeof(int));
usa_pointer->GDPPerCapita = (int*)malloc(sizeof(int));
usa_pointer->NetWealthTrillions = (int*)malloc(sizeof(int));

A.

*usa_pointer->GDPBillions = 22000;
*usa_pointer->GDPPerCapita = 70000;
*usa_pointer->NetWealthTrillions = 125;

B.

usa_pointer->GDPBillions = 22000;
usa_pointer->GDPPerCapita = 70000;
usa_pointer->NetWealthTrillions = 125;

C.

*usa_pointer->*GDPBillions = 22000;
*usa_pointer->*GDPPerCapita = 70000;
*usa_pointer->*NetWealthTrillions = 125;

D.

*usa_pointer.*GDPBillions = 22000;
*usa_pointer.*GDPPerCapita = 70000;
 *usa_pointer.*NetWealthTrillions = 125;

以上哪项语句为 USA 到 usa_pointer 的字段赋值？

Answer 1

分配内存于堆上。

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