c-<<运算符重写为cout int和double值
作者:互联网
我需要重写<<运算符,以便它可以表示小时(int)和温度(double)的值. 我想我已经包括了所有必要的部分.提前致谢.
struct Reading {
int hour;
double temperature;
Reading(int h, double t): hour(h), temperature(t) { }
bool operator<(const Reading &r) const;
};
========
ostream& operator<<(ostream& ost, const Reading &r)
{
// unsure what to enter here
return ost;
}
========
vector<Reading> get_temps()
{
// stub version
cout << "Please enter name of input file name: ";
string name;
cin >> name;
ifstream ist(name.c_str());
if(!ist) error("can't open input file ", name);
vector<Reading> temps;
int hour;
double temperature;
while (ist >> hour >> temperature){
if (hour <0 || 23 <hour) error("hour out of range");
temps.push_back( Reading(hour,temperature));
}
}
解决方法:
例如这样:
bool operator <(Reading const& left, Reading const& right)
{
return left.temperature < right.temperature;
}
并且它应该是一个全局函数(或与Reading相同的名称空间),而不是成员或Reading,如果您要拥有任何受保护的成员或私有成员,则应将其声明为朋友.可以这样完成:
struct Reading {
int hour;
double temperature;
Reading(int h, double t): hour(h), temperature(t) { }
friend bool operator <(Reading const& left, Reading const& right);
};
标签:ostream,c,iostream 来源: https://codeday.me/bug/20191013/1906542.html