C中对结构体sizeof

唉

#include<iostream>

using namespace std;

//1 Byte
struct test
{
    /* data */
};
//8 Byte
struct test2
{
    char a;
    int b;
};
//8 Byte
struct test3
{
    int a;
    char b;
};
//12 Byte
struct test4
{
    char c;
    int a;
    char b;
};
//8 Byte
struct test5
{
    char c;
    char b;
    int a;
};
//2 Byte
struct test6
{
    char a;
    char b;
};

//16 Byte
struct test7
{
    double a;
    char b;
};


int main(){

    cout<<sizeof(test)<<endl;
    cout<<sizeof(test2)<<endl;
    cout<<sizeof(test3)<<endl;
    cout<<sizeof(test4)<<endl;
    cout<<sizeof(test5)<<endl;
    cout<<sizeof(test6)<<endl;
    cout<<sizeof(test7)<<endl;
    return 0;
}

字节数据是存在内存中的，字节对齐能加快内存的访问速度。