[英]Invalid operands to binary expression
我收到以下錯誤:
二進制表達式(“
basic_ostream<char,std::_1::char_traits<char>>
'和'value_type
'(qElem
'))的無效操作數出現在以下位置:cout << "Your first task is to: " << tasks.front() << endl;
代碼建議我在&tasks.front()
處放置&
,但是我不想接收0xfdlkajd
的值,我想將第一個值存儲在向量中。 任何幫助將不勝感激。
我的代碼:
#ifndef Queue_queue_h
#define Queue_queue_h
#include <iostream>
#include <string>
#include <vector>
using namespace std;
struct qElem { //qElem Struct
string s;
string p;
qElem(string task, string priority) : s(task), p(priority) {}
};
//Establishing my Template and PriQueue Class
template <class T> //Template
class PriQueue
{
public:
vector<qElem> tasks;
//PriQueue();
void enqueue(T str, int pri); //Adds to queue
void dequeue(); //Deletes from queue
void peek(); //Prints the first value in queue
void size(); //Prints how many in queue
void sort(vector<qElem*> &tasks); //Sort according to priority
private:
int count = 0;
};
template <class T1>
void PriQueue<T1>::enqueue(T1 str, int pri) //Adding an element to the queue
{
tasks.push_back(qElem(str, pri));
sort(tasks); //NEW ERROR IS HERE
count++;
}
template <class T1>
void PriQueue<T1>::dequeue() //Removing an element from the front of the queue
{
//tasks.erase(tasks.begin());
tasks.erase(tasks.begin());
if (tasks.empty()) {
cout << "You have no tasks!" << endl;
}
else {
}
count--;
}
template <class T1>
void PriQueue<T1>::peek() //Returning a value at front of the queue (NOT removing it)
{
if (tasks.empty()) {
cout << "You have no tasks!" << endl;
}
else {
cout << "Your first task is to: " << tasks.front().s << endl;
}
//Testing Purposes only
/*
cout << "Your tasks are:";
for (typename vector<T1>::iterator i = tasks.begin() ; i != tasks.end(); ++i)
cout << " " << *i << ",";
cout << endl;
*/
}
template <class T1>
void PriQueue<T1>::size() //Returning the number of items in the queue.
{
cout << "You have " << count << " tasks in queue." << endl;
}
template <class T>
void PriQueue<T>::sort(vector<qElem*> &tasks) {
bool sortUp = true;
for(int i = 0; i < tasks.size();i++)
for(int j = i+1; j < tasks.size(); j++)
{
if(sortUp)
{
if(tasks[i] > tasks[j])
swap(tasks[i],tasks[j]);
}
else if(tasks[i] < tasks[j]) //else sortDown
swap(tasks[i],tasks[j]);
}
}
#endif
編譯器不知道如何打印出qElem
。 如果只想打印任務,請使用cout << "..." << tasks.front().s << endl;
。 編譯器知道如何打印std::string
。 (您也可以為qElem
實現自己的operator <<
重載,但是在這種情況下,這可能會過大。)
請注意,您的代碼有很多問題。 當您的qElem
僅存儲std::string
時,為什么使用模板PriQueue
? 為什么要使用類成員( ss
和pp
)在構造函數中存儲臨時值? 您的優先級是int
(構造函數)還是std::string
( qElem
)或T
?
qElem必須實現運算符<<
struct qElem { //qElem Struct
string s;
string p;
qElem(string task, string priority) : s(task), p(priority) {}
std::ostream& operator<<(std::ostream& os, const qElem & obj)
{
os << s << "/" << p;
return os;
}
};
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