编译器错误使用g ++

#include <iostream> 
using namespace std; 

class C 
{ 
    public: 
    virtual string toString() 
    { 
     return "class C"; 
    } 
}; 

class B : public C 
{ 
    public: 
    string toString() 
    { 
     return "class B"; 
    } 
}; 

class A : public B 
{ 
    public: 
    string toString() 
    { 
     return "class A"; 
    } 
}; 

void displayObject(C &p) 
{ 
    cout << p.toString << endl; 
} 

int main() 
{ 
    A a; 
    B b; 
    C c;  
    displayObject(a); 
    displayObject(b); 
    displayObject(c); 
    return 0; 
}

的错误编译器错误使用g ++

demo.cpp: In function ‘void displayObject(C&)’: 
demo.cpp:33: errors：no match for ‘operator<<’ in ‘std::cout << p->C::toString’ 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:108: 附注：备选为： std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:117: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ios<_CharT, _Traits>& (*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:127: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:165: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:169: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:173: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/ostream.tcc:91: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:180: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/ostream.tcc:105: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:191: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:200: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:204: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:209: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:213: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:221: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/ostream:225: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>] 
/usr/lib/gcc/i686-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/ostream.tcc:119: 附注：   std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_streambuf<_CharT, _Traits>*) [with _CharT = char, _Traits = std::char_traits<char>]

来源

2013-03-15 dclink

时后的toString这是一个格式化一团糟。 – Rapptz 2013-03-15 01:13:46

至少要努力使错误可读。 – 2013-03-15 01:14:14

尝试调用功能toString()，而不是打印出来：

cout << p.toString() << endl;

注意括号:)

打印它没有工作，因为没有流插入操作符重载采用类型std::string(C::*)()

来源

2013-03-15 01:14:15 sehe

您的指针到memberfunction忘记了（）打印

来源

2013-03-15 01:14:55 cppguy

天啊！想 – dclink 2013-03-15 01:17:35

编译器错误使用g ++

回答

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