Cpp面试题（持续更新）
内存对齐
对齐规则:
1.基本类型的对齐值就是其sizeof值;
2.结构体的对齐值是其成员的最大对齐值，记为m;
3.编译器可以设置对齐值，方法为#pragma pack(n)n = 1,2,4,8,16；实际对齐值 = min{m, n}。
#include<iostream> using namespace std; struct{ char z; }A; struct{ short z; }B; struct{ int z; }C; struct{ float z; }D; struct{ double z; }E; struct{ long z; }F; struct{ char x; char y; }G; struct{ char x; short y; }H; struct{ char x; int y; }I; struct{ char x; long y; }J; struct{ char x; char y; char z; }K; struct{ char x; char y; long z; }L; struct{ char x; long y; char z; }M; int main() { cout<<"sizeof(A)="<<sizeof(A)<<endl; // 1 cout<<"sizeof(B)="<<sizeof(B)<<endl; // 2 cout<<"sizeof(C)="<<sizeof(C)<<endl; // 4 cout<<"sizeof(D)="<<sizeof(D)<<endl; // 4 cout<<"sizeof(E)="<<sizeof(E)<<endl; // 8 cout<<"sizeof(F)="<<sizeof(F)<<endl; // 8 cout<<"sizeof(G)="<<sizeof(G)<<endl; // 2 cout<<"sizeof(H)="<<sizeof(H)<<endl; // 4 cout<<"sizeof(I)="<<sizeof(I)<<endl; // 8 cout<<"sizeof(J)="<<sizeof(J)<<endl; // 16 cout<<"sizeof(K)="<<sizeof(K)<<endl; // 3 cout<<"sizeof(L)="<<sizeof(L)<<endl; // 16 cout<<"sizeof(M)="<<sizeof(M)<<endl; // 24 return 0; }智能指针