隱式轉換 && explicit 顯示初始化

#include "stdafx.h"<br />#include <iostream><br />#include <string></p><p>using namespace std;</p><p>class A<br />{<br />public:<br />int iNum;<br />A(){}</p><p>explicit A( class B& b); // 用exlicit 顯示初始化<br />//A( class B& b);<br />};</p><p>class B<br />{<br />public:<br />int iNum;<br />double dNum;</p><p>B(){}</p><p>operator A()<br />{<br />A a;<br />a.iNum = this->iNum;</p><p>cout<<"World !"<<endl;<br />return a;<br />}</p><p>operator double()<br />{<br />return 1.0;<br />}</p><p>B& operator = (double const d)<br />{<br />this->dNum = d;<br />return *this;<br />}<br />};</p><p>A::A(B& b)<br />{<br />this->iNum = b.iNum;</p><p>cout<<"Hello "<<endl;<br />}</p><p>void aa(A asd){}</p><p>int main()<br />{<br />B b;<br />b.iNum = 100;</p><p>double d = b;<br />d = b;<br />b = d;</p><p>//A a( b );<br />//aa(b);<br />A a = b;<br />cout<<a.iNum<<endl;</p><p>system("PAUSE");<br />return 0;<br />}<br />

// 隱式轉換1</p><p>#include <iostream><br />#include <string></p><p>using namespace std;</p><p>class B<br />{<br />public:<br /> int iNum;<br />};</p><p>class A<br />{<br />public:<br /> int iNum;<br /> A( const B &b )<br /> {<br /> iNum = b.iNum;<br /> }</p><p>/*A& operator = ( const B& b)<br />{<br /> this->iNum = b.iNum;<br /> return *this;<br />}*/<br />};</p><p>int main()<br />{<br /> B b;<br /> b.iNum = 100;<br /> A a(b);<br /> cout<<a.iNum;<br /> system("PAUSE");<br /> return 0;<br />}</p><p>

// 隱式轉換2</p><p>#include <iostream><br />#include <string></p><p>using namespace std;</p><p>class B<br />{<br />public:<br /> int iNum;<br />};</p><p>class A<br />{<br />public:<br /> int iNum;<br /> /*A( const B &b )<br /> {<br /> iNum = b.iNum;<br /> }*/</p><p>A& operator = ( const B& b)<br />{<br /> this->iNum = b.iNum;<br /> return *this;<br />}<br />};</p><p>int main()<br />{<br /> B b;<br /> b.iNum = 100;<br /> A a;<br /> a = b;<br /> cout<<a.iNum;<br /> system("PAUSE");<br /> return 0;<br />}</p><p>