ostream 运算符<< 为获取 STL 容器而过载，传递 std：：string 会破坏它？

ostream operator<< overloaded for taking STL containers, passing std::string breaks it?

本文关键字：lt string 传递 std 获取 运算符 STL ostream      更新时间：2023-10-16

所以我重载了 ostream <<运算符，以便它可以获取大多数 STL 容器并打印它们。但是，它不适用于传递字符串(错误是行"cout <<s;"的"不明确的重载"(。如何使它像没有过载一样在字符串上工作？

#include <bits/stdc++.h>
using namespace std;
template<typename T>
ostream& _containerprint(ostream &out, T const &val) {
return (out << val << " ");
}
template<typename T1, typename T2>
ostream& _containerprint(ostream &out, pair<T1, T2> const &val) {
return (out << "{" << val.first << " " << val.second << "} ");
}
template<template<typename, typename...> class TT, typename... Args>
ostream& operator<<(ostream &out, TT<Args...> const &cont) {
for(auto&& elem : cont) {
_containerprint(out, elem);
}
return out;
}
int main() {
string s = "help me";
cout << s;
}

编辑：请不要再吓坏了，#include <bits/stdc++.h>是因为这是为了编程比赛设置;真的没关系！

>std::string是一个模板类(别名std::basic_string<char>(

所以std::cout << s匹配你的过载和std::basic_string<T>的超载.

没有一个过载比另一个更专业。

可能的解决方法是为std::string添加额外的重载：

std::ostream& operator << (std::ostream& out, const std::string& s)
{
return operator << <char>(out, s);
// Select template <class CharT, class Traits, class Allocator>
// std::basic_ostream<CharT, Traits>& 
// operator<<(std::basic_ostream<CharT, Traits>& os,
//            const std::basic_string<CharT, Traits, Allocator>& str);
}

演示

使ostream参数更通用，以便重载比std::string的标准重载更通用。

template<typename CharT, typename Traits, typename T>
ostream& _containerprint(std::basic_ostream<CharT, Traits> &out, T const &val) {
return (out << val << " ");
}
template<typename CharT, typename Traits, typename T1, typename T2>
ostream& _containerprint(std::basic_ostream<CharT, Traits> &out, pair<T1, T2> const &val) {
return (out << "{" << val.first << " " << val.second << "} ");
}
template<typename CharT, typename Traits, template<typename, typename...> class TT, typename... Args>
ostream& operator<<(std::basic_ostream<CharT, Traits> &out, TT<Args...> const &cont) {
for(auto&& elem : cont) {
_containerprint(out, elem);
}
return out;
}
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