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