在我的机器上，下面附的程序打印1，2，3，4。这是一般预期的行为吗，还是

struct {
    Vector position;
    Vector velocity;
    Vector acceleration;
};

字符串
不同于…的衬垫

struct {
    double x;
    double y;
    double dxdt;
    double dydt;
};

型
由于结构体的嵌套？通常，所有成员具有相同类型的结构：

struct {
 Type member1;
 Type member2;
 ... 
 Type memberN;
}

型
具有与嵌套结构相同的内存布局

struct {
 struct group1 { 
    Type member1;
    Type member2;
    ...
    Type memberI};
 };
 struct group2 { 
    Type memberIplus1;
    Type memberIplus2;
    ...
    Type memberIplusJ};
 };
 ...
 struct groupM {
    ...
    Type memberN
 };
}

型
附加程序：

#include <stdio.h>

typedef struct vector {
    double x;
    double y;
} Vector;

typedef union {
    struct {
        Vector position;
        Vector velocity;
        Vector acceleration;
    };
    struct {
        double x;
        double y;
        double dxdt;
        double dydt;
    };
} State;

int main() {
 State state = {
    .position = {1,2},
    .velocity = {3,4},
 };
 printf("%0.f\n",state.x);
 printf("%0.f\n",state.y);
 printf("%0.f\n",state.dxdt);
 printf("%0.f\n",state.dydt);
 return 1;
}

型