Question

#ifndef SALESITEM_H
#define SALESITEM_H
#include <iostream>
#include <string>
using namespace std;
class Sales_data
{
public:
    Sales_data(unsigned num,int pr , string isb):units_sold(num),price(pr),isbn(isb)
{
    cout<<"it works"<<endl;
};
    Sales_data() = default;
    Sales_data& combine(const Sales_data& rhs);

    string Getisbn() ;
    int Getprice() ;
    unsigned Getunits_sold();


private:
    unsigned units_sold;
    int price;
    string isbn;
};
Sales_data& Sales_data::combine(const Sales_data& rhs)
{
    units_sold += rhs.units_sold;
    price += rhs.price;
    return *this;
}
string Sales_data::Getisbn()
{
    return isbn;
}
int Sales_data::Getprice()
{
    return units_sold;
}
unsigned Sales_data::Getunits_sold()
{
    return units_sold;
}
istream& read(istream& in,Sales_data &book)
{
    in >>book.Getisbn();
    return in;
}

它表示日志中的问题

在＆GT;＆GT; book.Getunits_sold（） /Users/apple/Desktop/shirley/shirley/Sales_item.h：185：8：无效操作数到二进制表达式（＆＃39; istream＆＃39;（又名＆＃39; basic_istream＆＃39;）和＆＃39;字符串＆＃39; （又名＆＃39; basic_string，分配器＆gt;＆＃39;））

Answer 1

我不知道为什么它说二元表达式（float和float）的运算符无效。非常感谢你！

int main(int argc, char** argv) {

    float a;
    float b;

    b = a - (int) a;

    printf("Write a number:");
    scanf("%f", &a);

    if ((b == 0)&&(b % 2 == 0)) {
        printf("It is an integer even number");
    } else if ((b == 0)&&(b % 2 != 0)) {
        printf("It is an integer odd number");
    } else {
        printf("It is a real number");
    }

    return (EXIT_SUCCESS);
}

二进制表达式的操作数无效：

1 个答案: