Re: [問題] 關於Class指標的觀念

看板C_and_CPP (C/C++)作者descent (「雄辯是銀，沉默是金」)時間11年前 (2013/08/30 11:54)推噓0(0推 0噓 5→)

留言5則, 2人參與討論串11/19 (看更多)

vc 版本, 運氣很好, 沒花太久時間。 vc 我不熟, 有什麼問題還請版友們提出。 env: vc2010 winxp 32bit #include <iostream> #include <cstdio> using namespace std; struct A { virtual void func() { printf("i: %d\n", i_); } void inc() { ++i_; } A() { i_=10; } private: int i_; }; int main() { void (A::*p)() = &A::func; //cout << "sizeof: " << sizeof(p) << endl; //cout << "sizeof: " << sizeof(A) << endl; //printf("addr: %p\n", p); //cout << "p:" << p << endl; //unsigned int addr = pp; //printf("addr: %p\n", pp); A a; (a.*p)(); unsigned int vptr_addr = *(unsigned int *)&a; cout << "vptr_addr:" << hex << vptr_addr << endl; unsigned int func_addr = *(unsigned int *)vptr_addr; cout << "func_addr:" << hex << func_addr << endl; a.inc(); __asm { lea ecx, a } #if 1 (*(void(*)())(func_addr) )(); A aa; __asm { lea ecx, aa } (*(void(*)())(func_addr) )(); __asm { lea ecx, a } (*(void(*)())(func_addr) )(); __asm { lea ecx, aa } (*(void(*)())(func_addr) )(); #endif return 0; } C:\>cl□ c.cpp Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86 Copyright (C) Microsoft Corporation.□ All rights reserved. c.cpp C:\Program Files\Microsoft Visual Studio 10.0\VC\INCLUDE\xlocale(323) : warning C4530: 已使用 C++ 例外處理常式，但沒有啟用回溯語意 (Unwind Semantics)。請指定 /E Hsc Microsoft (R) Incremental Linker Version 10.00.30319.01 Copyright (C) Microsoft Corporation.□ All rights reserved. /out:c.exe c.obj C:\>c i: 10 vptr_addr:41a1bc func_addr:4011a0 i: 11 i: 10 i: 11 i: 10 順便測試了 arm/g++ arm version by c++ c.arm: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.26, not stripped root@/home$ ./c.arm i: 10 vptr_addr:8cc8 func_addr:8b74 i: 11 i: 10 i: 11 i: 10 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 59.125.239.46 ※ 編輯: descent 來自: 59.125.239.46 (08/30 11:58)