学步园

在定义于类外部的成员函数中，形参表和成员函数体都出现在成员名之后。这些都是在类作用域中定义，所以可以不用限定而引用其他成员。例如类Screen中的get的二形参版本的定义，该函数用Screen内定义的index类型来指定其参数类型。因为形参表在Screen类的作用域内，所以不必要指明我们想要的Screen：：index。我们想要的是定义在当前类作用域中的，这是隐含的。同样，使用index、width、和contents时指的都是Screen类中声明的名字

#include <string>
#include <iostream>
using namespace std;  

class Screen {
public:
    typedef std::string::size_type index;
    inline char get(index ht, index wd) const;
    Screen():contents("liaojianguo dabendan"), height(1), width(1) { }
private:
    std::string contents;
    index height, width;
};

char Screen::get(index r, index c) const
{
    index row = r * width; 
    return contents[row + c];
}


int main()
{
	Screen c1;
        cout << c1.get(1, 1) << endl;
}

输出：

pateo@pateo-B86N53X:~/work/study$ g++ main.cc -o main
pateo@pateo-B86N53X:~/work/study$ ./main
a

类成员中的名字查找

检查成员函数局部作用域中的声明

检查对所有类成员的声明

检查在此成员函数定义之前的作用域中出现的声明

#include <string>
#include <iostream>
using namespace std;  

int i = 1;

class Screen {
public:
    typedef std::string::size_type index;
    inline char get(index ht, index wd) ;
    Screen():contents("liaojianguo dabendan"), height(1), width(1) { }
private:
    std::string contents;
    index height, width;
};

Screen::index set(Screen::index);

char Screen::get(index r, index c) 
{
    index row = r * width; 
    return contents[row + c - i];
}

int main()
{
	Screen c1;
        cout << c1.get(1, 1) << endl;
}

输出：

pateo@pateo-B86N53X:~/work/study$ g++ main.cc -o main
pateo@pateo-B86N53X:~/work/study$ ./main
i
pateo@pateo-B86N53X:~/work/study$ 

#include <string>
#include <iostream>
using namespace std;  

int i = 1;

class Screen {
public:
    typedef std::string::size_type index;
    inline char get(index ht, index wd) ;
    Screen():contents("liaojianguo dabendan"), height(1), width(1) { }
private:
    std::string contents;
    index height, width;
};

Screen::index set(Screen::index);

Screen::index set(Screen::index i)
{
	cout << "--------------" << endl;
        return i + 2;
}

char Screen::get(index r, index c) 
{
    index row = r * width; 
    row = set(row);
    return contents[row + c - i];
}

int main()
{
	Screen c1;
        cout << c1.get(1, 1) << endl;
	
}

输出：

pateo@pateo-B86N53X:~/work/study$ g++ main.cc -o main
pateo@pateo-B86N53X:~/work/study$ ./main
--------------
o
pateo@pateo-B86N53X:~/work/study$