为什么没有to_string（const string&）？ [英] Why is there no to_string(const string&)?

问题描述

我有模板代码，需要将某些模板类型转换为字符串。为此，我为自己的类型重载了to_string。但是类型也可以是字符串。然后编译失败，因为类型字符串本身没有to_string的重载（只是返回其参数）。

I have template code which needs to convert some template type to string. For this I overload to_string for my own types. But the type can also be a string already. Then compilation fails, because there is no overload of to_string for type string itself (just returning its argument).

edit：
示例代码：

edit: example code:

template<class T>
class TemplatedClass
{
public:

string toString() const
{
    // this should work for both simple types like int, double, ...
    // and for my own classes which have a to_string overload
    // and also for string, which is the reason for my question
    return string("TemplatedClass: ").append(to_string(t_));
}

private:
    T t_;
};

推荐答案

您可以编写带有适当重载的模板化函数如下：

You can just write your own templated function with proper overloads as follows:

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

template<typename T>
std::string toString(const T& t) {
    return std::to_string(t);
}

std::string toString(const char* t) {
    return t;
}

std::string toString(const std::string& t) {
    return t;
}


int main() {
    cout << toString(10) << endl;
    cout << toString(1.5) << endl;
    cout << toString("char*") << endl;
    cout << toString(std::string("string")) << endl;
    return 0;
}

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