错误:与"operator<<"不匹配(操作数类型为"std :: ostream {aka std :: basic_ostream< char>}"和"void") [英] error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream<char>}’ and ‘void’)

问题描述

这是我的代码(仅写本质)，我明白了:

错误:"operator<<"不匹配(操作数类型为"std :: ostream {aka std :: basic_ostream}"和"void")

  Mobil类{上市:void print()const;int getNumber()const;double getData()const;朋友ostream&运算符<<(ostream& ;, const Mobil& amp;);};上游&运算符<("ostream& out，const Mobil& mobil"){出<<mobil.print()<<恩德尔退回} 

出什么问题了?

解决方案

问题是此行: out<<mobil.print()<<endl; .您的 print()方法不会返回任何内容(类型为 void )，因此无法将其发送到 ostream .

要解决此问题，您的 print()方法应以 ostream 支持的一种类型返回要打印的内容，您可以在参考.

This is my code (I write the essence only) and I get this:

error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream}’ and ‘void’)

class Mobil {
public:
void print() const; 
int  getNumber() const;
double getData() const;
friend ostream& operator <<(ostream&, const Mobil&);
};

ostream& operator<<(ostream& out, const Mobil& mobil) {
    out << mobil.print() << endl;
    return out;
}

what is the problem?

解决方案

Problem is this line: out << mobil.print() << endl;. Your print() method doesn't return anything (is type of void), so it can't be send to ostream.

To solve this problem, your print() method should return whatever you want to printout in one of types supported by ostream which you can find in reference.

这篇关于错误:与"operator&lt;&lt;"不匹配(操作数类型为"std :: ostream {aka std :: basic_ostream&lt; char&gt;}"和"void")的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！