可能重载operator *到多个int和一个char *？ [英] Possible to overload operator* to multiple an int and a char*?

问题描述

我想获得功能，所以我可以这样做：

I would like to get functionality so I can do this:

std::cout << "here's a message" << 5*"\n";

我尝试了以下操作：

std::string operator* (int lhs, const char* rhs) {
  std::string r = "";
  for(int i = 0; i < lhs; i++) {
    r += rhs;
  }
  return r;
}

我收到此错误消息：

error: ‘std::string operator*(int, const char*)’ must have an argument of class or enumerated type

根据此SO职位中的答案什么'必须有类或枚举类型的参数'实际上意味着什么它几乎看起来像我不能做这一时期。这是真的吗？

According to the answers in this SO post What does 'must have an argument of class or enumerated type' actually mean it almost seems like I can't do this period. Is that really the case? If not, how do I fix this or arrange a workaround?

我知道我可以做的是有 rhs 作为 std :: string ，但是整个练习的一半被放弃，因为 5 * std :: string（\\\
）很笨重。

What I know I can do is have rhs as a std::string, but then the whole point of the exercise is half foregone, as 5*std::string("\n") is quite clunky.

推荐答案

你应该能够使用用户定义的文字。例如：

You should be able to achive it with user-defined literals. For instance:

#include <iostream>
#include <string>


std::string operator"" _s(const char* s) { return std::string(s); }

std::string operator"" _s(const char* s, std::size_t len) { return std::string(s, len); }

std::string operator* (unsigned int k, std::string s) {
    std::string t;
    for (unsigned int i = 0; i < k; ++i) 
        t += s;

    return t;
}

std::string operator* (std::string s, unsigned int k) { return k * s; }

int main() {
    std::cout << "Jump!"_s * 5 << "\n";
}

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