sizeof的问题

1. 在32位平台上，有如下的输出是：

 

#include <iostream>

using namespace std;

void foo(char array4[10]){

    cout << sizeof(array4) << endl;

}

int main(){

    char array1[10] = "hello";
    char array2[] = "hello";

    char array3[2][3] = {"ab", "cd"};
    char *p=array1;

    cout << sizeof(array1) << endl;
    cout << sizeof(array2) << endl;

    cout << sizeof(array3) << endl;
    cout << sizeof(p) << endl;
    foo(array1);

}

 

 

2. 在Win32平台上，如下程序的输出是：

#include <iostream>

using namespace std;

struct MyStruct1{
    char a;
    int b;
};

struct MyStruct2{
    int a;
    char b;
};

struct MyStruct3{
    int a;
    char b;
    double c;
};

struct MyStruct4{
    char a;
    MyStruct3 s3;
};

int main(){

    cout << sizeof(MyStruct1) << endl;
    cout << sizeof(MyStruct2) << endl;
    cout << sizeof(MyStruct3) << endl;
    cout << sizeof(MyStruct4) << endl;
}

 

 

【参考】

1. Struct 对齐问题：http://blog.youkuaiyun.com/lbjfeng/archive/2009/03/04/3952387.aspx