* 指针简单总结
//接受命令行参数的函数int main( int argc/*字符串的个数,>=1*/, char * argv[]/*指向字符串*/ ){ //参数的个数:argc-1 //参数:argv[1~n] cout << sizeof("goodbye");//输出8 }
引用:给旧变量起新名字,通过新名字操作旧变量.
引用和用来初始化它的变量是同一个实体.
引用不会复制数据,提高了效率.
传数组一般不用引用.直接传数组名
sizeof(类型)//只关心类型,不关心内容//示例代码int x=0;cout << sizeof(1/x) << endl;//输出4int (&p)[10] //数组引用,没必要这样写,建议不使用,注意数组名不是变量 //没必要为其起别名(int * p, int n ) //这样写比较好
函数指针:像声明函数一样定义函数指针,把函数名改成(*指针),占4个字节,因为它是一个指针.
函数调用:fp( /* args */ )
void 指针把类型信息给丢了.
没有类型的指针不能用来表示变量,所以用void指针时一定要强转 *(A*)p
指针有两点:1,保存地址 2,类型一致
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*** 面向对象编程
//时钟程序//clock.h#define _CLOCK_H_struct Time{ int hour; int minute; int second;};void set( Time* p, int h, int m, int s );void tick( Time* p );void show( Time* p );void run( Time* p );#endif//clock.cc#include "clock.h"#include <ctime>#include <iostream>using namespace std;void set( Time* p, int h, int m, int s ){ p->hour = h; p->minute = m; p->second = s;}void tick( Time* p ){ long t = time(NULL); while( t == time(NULL) ); if( ++p->second >=60 ){ p->second = 0; if( ++p->minute >= 60 ){ p->minute = 0; if( ++p->hour >=24 ){ p->hour = 0; } } }}void show( Time* p ){ cout << '\r'; if( p->hour < 10 ) cout << 0; cout << p->hour << ':'; if( p->minute <10 ) cout << 0; cout << p->minute << ':'; if( p->second <10 ) cout << 0; cout << p->second << flush;}void run( Time* p ){ for(;;){ tick( p ); show( p ); }}//main.cc#include "clock.h"using namespace std;int main(){ Time t; set( &t,21,35,55 ); run( &t );}
//时钟程序 改进型//main.cc#include "clk.h"using namespace std;int main(){ Time t; t.set( 21,35,55 ); t.run( );}//这个地方用了VI一条替换的命令,将上面的程序中的所有的p替换成this//1,$s/p/this/g//clk.h#ifndef _CLOCK_H_#define _CLOCK_H_struct Time{ int hour; int minute; int second; void set( int h, int m, int s ); void tick( ); void show( ); void run( );};#endif//clk.cc#include "clk.h"#include <ctime>#include <iostream>using namespace std;void Time::set( int h, int m, int s ){ this->hour = h;//this可省略不写 this->minute = m; this->second = s;}void Time::tick( ){ long t = time(NULL); while( t == time(NULL) ); if( ++this->second >=60 ){ this->second = 0; if( ++this->minute >= 60 ){ this->minute = 0; if( ++this->hour >=24 ){ this->hour = 0; } } }}void Time::show( ){ cout << '\r'; if( this->hour < 10 ) cout << 0; cout << this->hour << ':'; if( this->minute <10 ) cout << 0; cout << this->minute << ':'; if( this->second <10 ) cout << 0; cout << this->second << flush;}void Time::run( ){ for(;;){ tick( ); show( ); }}
//clk.h改进成类#ifndef _CLOCK_H_#define _CLOCK_H_class Time{ int hour; int minute; int second;public: void set( int h, int m, int s ); void tick( ); void show( ); void run( );};#endif
在成员函数中,把用来调用这成员函数的变量称为当前变量(this总是指向当前变量)
*this 就表示当前变量.
相关资源：用C-语言实现面向对象编程.pdf
