C++PRIMER第五版练习题答案第一章

C++PRIMER第五版练习题答案第一章

应该有很多小伙伴和我一样,闲来无事买了本C++的书自己啃,课后的练习题做的很揪心,这里我分享下我写的答案,希望能帮助到你,提供源码,就不跑了哈,毕竟现在是第一章,很很很基础,当看到后面,分享到后面的时候,注释会写详细点方便大家一起讨论思考~~

1.1

int main()
{
    return 0;
}

1.2

int main()
{
    return -1;
}

1.3

#include <iostream>
int main()
{
    std::cout<<"Hello,World"<<std::endl;
    return 0;
}

1.4

#include <iostream>
int main()
{
    int i=0,j=0;
    std::cin>>i>>j;
    std::cout<<"The ji of "<<i<<" * "<<j<<" is "<<i*j<<std::endl;
    return 0;
}

1.5

#include <iostream>
int main()
{
    int i=0,j=0;
    std::cin>>i>>j;
    std::cout<<"The ji of ";
    std::cout<<i;
    std::cout<<" * ";
    std::cout<<j;
    std::cout<<" is ";
    std::cout<<i*j<<std::endl;
    return 0;
}

1.6

/*
    不合法,找不到cout输出,<<符号左侧应都加上std::cout
*/

1.7

/*
 *下列行为不允许发生,注释界定符不可嵌套
 * /* */
 *
 * /

int main()
{
    return 0;
}

1.8

#include <iostream>
int main()
{
    std::cout<<"/*"; //可
    std::cout<<"*/"; //可
    std::cout<</*"*/"*/; //不可
    std::cout<</*"*/"/*"/*"*/; //可
}

1.9

#include <iostream>
int main()
{
    int sum=0,val=50;
    while (val<=100)
    {
        sum+=val;
        ++val;
    }
    std::cout<<"The sum of 50 to 100 is "<<sum<<std::endl;
    return 0;

}

1.10

#include <iostream>
int main()
{
    int val=10;
    while (val>=0)
    {
    std::cout<<"value is "<<val<<"\n"<<std::endl;
    --val;
    }
    return 0;

}

1.11++

#include <iostream>
int main()
{
    int i=0,j=0;
    std::cout<<"please input two numbers and i will give you the num in thems"<<std::endl;
    std::cin>>i>>j;
    if (i>=j)
    {
       while (i>=j)
    {
    std::cout<<"value is "<<i<<"\n"<<std::endl;
    --i;
    }
    }
    else
    {
        while (i<=j)
    {
    std::cout<<"value is "<<j<<"\n"<<std::endl;
    --j;
    }
    }
    return 0;

}

1.12

#include <iostream>
int main()
{
    int sum=0;
    for(int i=-100;i<=100;++i)
    {
        sum+=i;
    }
    std::cout<<"The sum is "<<sum<<std::endl;
}

1.13

#include <iostream>
int main()
{
    int sum=0,val=50;
    for(;val<=100;++val)
        sum+=val;
    std::cout<<"The sum of 50 to 100 is "<<sum<<std::endl;

    int valu=10;
    for (;valu>=0;--valu)
        std::cout<<"value is "<<valu<<"\n"<<std::endl;
    int i=0,j=0;
    std::cout<<"please input two numbers and i will give you the num in thems"<<std::endl;
    std::cin>>i>>j;
    if (i>=j)
    {
       for (;i>=j;--i)
            std::cout<<"value is "<<i<<"\n"<<std::endl;
    }
    else
    {
        for (;i<=j;--j)
            std::cout<<"value is "<<j<<"\n"<<std::endl;
    }
    return 0;
}

1.14

// for循环和while循环的优缺点如下：
// 1、在for循环中，循环控制变量的初始化和修改都放在语句头部分，形式较简洁，且特别适用于循环次数已知的情况。
// 2、在while循环中，循环控制变量的初始化一般放在while语句之前，循环控制变量的修改一般放在循环体中，形式上不如for语句简洁，但它比较适用于循环次数不易预知的情况（用某一条件控制循环）。
// 3、两种形式各有优点，但它们在功能上是等价的，可以相互转换。

1.15

// 编译器各类错误
// 1.语法错误
// 2.类型错误
// 3.声明错误

1.16

#include <iostream>
int main()
{
    int sum=0,value = 0;
    std::cout<<"I will print your sum and you can input not integer num to end\n";
    while (std::cin>>value)
        sum+=value;
    std::cout<<"The sum is "<<sum<<std::endl;
    return 0;
}

1.17&1.18

#include <iostream>
int main()
{
    int currVal = 0, val = 0;
    if (std::cin >> currVal)
    {
        int cnt = 1;
        while (std::cin >> val)
        {
            if (val == currVal)
            {
                ++cnt;
            }
            else
            {
                std::cout << currVal << " occurs " << cnt << " times " << std::endl;
                currVal = val;
                cnt = 1;
            }
        }
        std::cout << currVal << " occurs " << cnt << " times " << std::endl;
    }
    return 0;
}

1.19

#include <iostream>
int main()
{
    int i=0,j=0;
    std::cout<<"please input two numbers and i will give you the num in thems"<<std::endl;
    std::cin>>i>>j;
    if (i>=j)
    {
       while (i>=j)
    {
    std::cout<<"value is "<<i<<"\n"<<std::endl;
    --i;
    }
    }
    else
    {
        while (i<=j)
    {
    std::cout<<"value is "<<j<<"\n"<<std::endl;
    --j;
    }
    }
    return 0;

}

1.20

#include <iostream>
#include "Sales_item.h"
int main()
{
    Sales_item book;
    std::cout <<"input Ctrl+Z exit "<<std::endl;
    while (std::cin >> book)
    {
    std::cout << book <<std::endl;
    }
    return 0;
}

1.21

#include <iostream>
#include "Sales_item.h"
int main()
{
    Sales_item book1,book2;
    std::cin >> book1 >> book2;
    if (book1.isbn() == book2.isbn())
    {
        std::cout << book1 + book2 << std::endl;
        return 0;
    }
    else
    {
        std::cout << "Please input have same isbn data" << std::endl;
        return -1;
    }
}

1.22

#include <iostream>
#include "Sales_item.h"
int main()
{
    Sales_item total;
    std::cout <<"Please input same data and then input not same data output and then input Ctrl+Z exit "<<std::endl;
    if (std::cin >> total)
    {
        Sales_item trans;
        while (std::cin >> trans)
        {
            if (total.isbn() == trans.isbn())
            {
                total += trans;
            }
            else
            {
                std::cout << total <<std::endl;
            }
        }
    }
    return 0;
}

1.23

#include <iostream>
#include "Sales_item.h"
int main()
{
    Sales_item total;
    std::cout <<"Please input same data and then input not same data output and then input Ctrl+Z exit "<<std::endl;
    if (std::cin >> total)
    {
        Sales_item trans;
        int cnt = 1;
        while (std::cin >> trans)
        {
            if (total.isbn() == trans.isbn())
            {
                //total += trans;
                ++cnt;
            }
            else
            {
                std::cout << total.isbn() << " occours " << cnt << " times " <<std::endl;
                total = trans;
                cnt = 1;
            }
        }
        std::cout << total.isbn() << " occours " << cnt << " times " <<std::endl;
    }
    return 0;
}

1.24

#include <iostream>
#include "Sales_item.h"
/**
 * @brief 文件重定向: $ addItems <infile>outfile
 * 此处我们控制台查看一下测试的文件内容,然后再重定向,再看一下重定向里的内容
 * 1.   type book_sales.txt
 * 2.   1.24.exe <book_sales.txt>1.24.txt
 * 3.   type 1.24.txt
 *
 *
 */

int main()
{
    Sales_item total;
    std::cout <<"Please input same data and then input not same data output and then input Ctrl+Z exit "<<std::endl;
    if (std::cin >> total)
    {
        Sales_item trans;
        int cnt = 1;
        while (std::cin >> trans)
        {
            if (total.isbn() == trans.isbn())
            {
                //total += trans;
                ++cnt;
            }
            else
            {
                std::cout << total.isbn() << " occours " << cnt << " times " <<std::endl;
                total = trans;
                cnt = 1;
            }
        }
        std::cout << total.isbn() << " occours " << cnt << " times " <<std::endl;
    }
    return 0;
}

1.25

#include <iostream>
#include "Sales_item.h"
int main()
{
    Sales_item total;
    if (std::cin >> total)
    {
        Sales_item trans;
        while (std::cin >> trans)
        {
            if (total.isbn() == trans.isbn())
            {
                total += trans;
            }
            else
            {
                std::cout << total << std::endl;
                total = trans;
            }
        }
        std::cout << total << std::endl;
    }
    else
    {
        std::cerr << "No data?!" << std::endl;
        return -1;
    }
    return 0;
}

最后的这个头文件也就是我们要导入的,买书的应该都知道怎么下,这里贴一下源码~~

Sales_item.h

/*
 * This file contains code from "C++ Primer, Fifth Edition", by Stanley B.
 * Lippman, Josee Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 *
 * "Copyright (c) 2013 by Objectwrite, Inc., Josee Lajoie, and Barbara E. Moo."
 *
 *
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 *
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *
 *     Pearson Education, Inc.
 *     Rights and Permissions Department
 *     One Lake Street
 *     Upper Saddle River, NJ  07458
 *     Fax: (201) 236-3290
*/ 

/* This file defines the Sales_item class used in chapter 1.
 * The code used in this file will be explained in
 * Chapter 7 (Classes) and Chapter 14 (Overloaded Operators)
 * Readers shouldn't try to understand the code in this file
 * until they have read those chapters.
*/

#ifndef SALESITEM_H
// we're here only if SALESITEM_H has not yet been defined
#define SALESITEM_H

// Definition of Sales_item class and related functions goes here
#include <iostream>
#include <string>

class Sales_item {
// these declarations are explained section 7.2.1, p. 270
// and in chapter 14, pages 557, 558, 561
friend std::istream& operator>>(std::istream&, Sales_item&);
friend std::ostream& operator<<(std::ostream&, const Sales_item&);
friend bool operator<(const Sales_item&, const Sales_item&);
friend bool
operator==(const Sales_item&, const Sales_item&);
public:
    // constructors are explained in section 7.1.4, pages 262 - 265
    // default constructor needed to initialize members of built-in type
    Sales_item() = default;
    Sales_item(const std::string &book): bookNo(book) { }
    Sales_item(std::istream &is) { is >> *this; }
public:
    // operations on Sales_item objects
    // member binary operator: left-hand operand bound to implicit this pointer
    Sales_item& operator+=(const Sales_item&);

    // operations on Sales_item objects
    std::string isbn() const { return bookNo; }
    double avg_price() const;
// private members as before
private:
    std::string bookNo;      // implicitly initialized to the empty string
    unsigned units_sold = 0; // explicitly initialized
    double revenue = 0.0;
};

// used in chapter 10
inline
bool compareIsbn(const Sales_item &lhs, const Sales_item &rhs)
{ return lhs.isbn() == rhs.isbn(); }

// nonmember binary operator: must declare a parameter for each operand
Sales_item operator+(const Sales_item&, const Sales_item&);

inline bool
operator==(const Sales_item &lhs, const Sales_item &rhs)
{
    // must be made a friend of Sales_item
    return lhs.units_sold == rhs.units_sold &&
           lhs.revenue == rhs.revenue &&
           lhs.isbn() == rhs.isbn();
}

inline bool
operator!=(const Sales_item &lhs, const Sales_item &rhs)
{
    return !(lhs == rhs); // != defined in terms of operator==
}

// assumes that both objects refer to the same ISBN
Sales_item& Sales_item::operator+=(const Sales_item& rhs)
{
    units_sold += rhs.units_sold;
    revenue += rhs.revenue;
    return *this;
}

// assumes that both objects refer to the same ISBN
Sales_item
operator+(const Sales_item& lhs, const Sales_item& rhs)
{
    Sales_item ret(lhs);  // copy (|lhs|) into a local object that we'll return
    ret += rhs;           // add in the contents of (|rhs|)
    return ret;           // return (|ret|) by value
}

std::istream&
operator>>(std::istream& in, Sales_item& s)
{
    double price;
    in >> s.bookNo >> s.units_sold >> price;
    // check that the inputs succeeded
    if (in)
        s.revenue = s.units_sold * price;
    else
        s = Sales_item();  // input failed: reset object to default state
    return in;
}

std::ostream&
operator<<(std::ostream& out, const Sales_item& s)
{
    out << s.isbn() << " " << s.units_sold << " "
        << s.revenue << " " << s.avg_price();
    return out;
}

double Sales_item::avg_price() const
{
    if (units_sold)
        return revenue/units_sold;
    else
        return 0;
}
#endif