C++ Primer第一章 快速入门课后习题代码(2)

{std::cout<

std::cout<

system(\ return 0; }

#include #include

#include \int main() {

Sales_item book;

//读入ISBN，售出书的本数，销售价格 std::cout<<\ while(std::cin>>book) {

//输出ISBN，售出书的本数，总收入，平均价格

std::cout<<\of copies sold,\revenue,and average price:\ <

std::cout<

system(\ return 0; }

//习题-1.22

#include #include\int main() {

Sales_item trans1,trans2; //读入交易

std::cout<<\ std::cin>>trans1>>trans2; if(trans1.same_isbn(trans2))

std::cout<<\ <<\

<<\ < std::cout<<\ <

//习题-1.23

#include #include\int main() {

Sales_item total,trans; if(std::cin>>total) {

while(std::cin>>trans)

if(total.same_isbn(trans)) total=total+trans; else{

std::cout<<\ return -1; }

std::cout<<\ <<\

<<\ <

std::cout<<\ return -1; }

system(\ return 0; }

//习题-1.24

#include #include\int main() {

Sales_item trans1,trans2; int amount;

std::cout<<\ std::cin>>trans1; amount=1;

while(std::cin>>trans2)

if(trans1.same_isbn(trans2))//ISBN相同 ++amount; else{//ISBN不同

std::cout<<\ <

std::cout<<\ <

//习题-1.25

#include #include \

int main() {

// declare variables to hold running sum and data for the next record

Sales_item total, trans;

// is there data to process? if (std::cin >> total) {

// if so, read the transaction records while (std::cin >> trans)

if (total.same_isbn(trans))

// match: update the running total total = total + trans; else {

// no match: print & assign to total std::cout << total << std::endl; total = trans; }

// remember to print last record std::cout << total << std::endl; } else {

// no input!, warn the user

std::cout << \ return -1; // indicate failure }

return 0; }

/* 习题1.21~1.25要用到的头文件*/ #ifndef SALESITEM_H #define SALESITEM_H

// Definition of Sales_item class and related functions goes here

#include #include

class Sales_item {

friend bool operator==(const Sales_item&, const Sales_item&); // other members as before public:

// added constructors to initialize from a string or an istream Sales_item(const std::string &book):

isbn(book), units_sold(0), revenue(0.0) { } Sales_item(std::istream &is) { is >> *this; }

friend std::istream& operator>>(std::istream&, Sales_item&); friend std::ostream& operator<<(std::ostream&, const Sales_item&); public:

// operations on Sales_item objects

// member binary operator: left-hand operand bound to implicit this pointer