我希望有人能够回答为什么以下不起作用。不过请耐心等待,我仍然是个菜鸟……我只是无法弄清楚为什么会出现以下问题
using namespace std;
#include <string>
#include <iostream>
class testClass
{
public:
operator char* () {return (char*)"hi";};
operator int () {return 77;};
operator std::string () {return "hello";};
};
int main()
{
char* c;
int i;
std::string s = "goodday";
testClass t;
c = t;
i = t;
s = t;
cout<< "char: " << c << " int: " << i << " string: "<<s<<endl;
return 0;
}
给我一个编译时错误:
myMain.cpp: In function ‘int main()’:
myMain.cpp:23: error: ambiguous overload for ‘operator=’ in ‘s = t’
/usr/include/c++/4.2.1/bits/basic_string.h:500: note: candidates are: std::basic_string<_CharT, _Traits, _Alloc>& std::basic_string<_CharT, _Traits, _Alloc>::operator=(const std::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/include/c++/4.2.1/bits/basic_string.h:508: note: std::basic_string<_CharT, _Traits, _Alloc>& std::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/include/c++/4.2.1/bits/basic_string.h:519: note: std::basic_string<_CharT, _Traits, _Alloc>& std::basic_string<_CharT, _Traits, _Alloc>::operator=(_CharT) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
如果我不尝试分配
s = t;
它确实有效。
我已经尝试了几个小时甚至理解错误消息,但最让我困惑的是它确实适用于 char*。
我很感激任何提示。谢谢!马库斯