sizeof(struct)

• 在C语言中，结构体会以占用字节最长的变量为基准，做内存对齐。

#include<iostream>
#include<stdlib.h>
using namespace std;

struct A
{
    //4+4 = 8
    char c;
    int i;  
};

struct B
{
    //4+8+4 = 16 
    char c;
    A a;
    char b;
};

struct C
{
    //4 + 4*4 + 4 = 24
    char c;
    int a[4];
    int i;  
};

struct D
{   
    //4 + 4 = 8
    char c;
    char b;
    int q;  
};

struct E
{
    //8+8 = 16,以最大的为准，进行对齐填充 
    int a;
    double b;   
};

struct F
{   
    //1 + 1 = 2
    char a;
    char b;
};

int main()
{   
    cout<<"the sizeof struct A: "<<sizeof(A)<<endl;
    cout<<"the sizeof struct B: "<<sizeof(B)<<endl;
    cout<<"the sizeof struct C: "<<sizeof(C)<<endl;
    cout<<"the sizeof struct D: "<<sizeof(D)<<endl;
    cout<<"the sizeof struct E: "<<sizeof(E)<<endl;
    cout<<"the sizeof struct F: "<<sizeof(F)<<endl;
    return 0;   
} 

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