哈工大c++教学课件.pdf

Pointer C Programming Language Li Hanjing 2009-11-9 知己知彼 1 1 1. Why do we need a pointer void swap (int a, int b) { int temp; temp = a; a = b; b =temp; } Passing by value! main() { int x = 4, y = 5; Passing by reference swap( x, y); with pointers? cout x; } 2009-11-9 知己知彼 2 a a 12 x 12 b 24 y 24 b X 12 y 24 2009-11-9 知己知彼 3 Why do we need a pointer void swap (int a, int b) { int temp; temp = a; a = b; b =temp; } a main() x 12 { int x = 4, y = 5; y 24 swap( x, y); b cout x; } 2009-11-9 知己知彼 4 Stories on pointers • “该程序执行了非法操作，即将关闭” – 这种错误几乎全是由指针和数组导致的 • 黑客攻击服务器利用的bug绝大部分都是指针和 数组造成的 2009-11-9 知己知彼 5 5 Stories on pointers • The favorite of C funs • 很多“Mission Impossible” 由指针完成 – 大多数语言都有无数的“不可能” – 而C语言是 •