C++ Primer(第五版) 第八章练习答案

C++ Primer(第五版) 第八章练习答案

8.1or2

#include 
#include 
#include 

using namespace std;

istream &print(istream &is, string &item);

int main()
{
     
    string str;
    print(cin, str);
    print(cin, str);

    return 0;
}

istream &print(istream &is, string &item)
{
     
    while (is >> item)
        ;
    // is.clear();

    is.clear(cin.rdstate() & ~is.failbit & ~is.eofbit);

    return is;
}

8.3

/**
 * 读入结尾符
 * 无法读取的数值
 */

8.4

#include 
#include 
#include 
#include 

using namespace std;

int main()
{
     
    ifstream input("test.txt");
    vector<string> vec;
    string str;

    while (getline(input, str))
        vec.push_back(str);

    for (auto &i : vec)
        cout << i << endl;

    return 0;
}

8.5

#include 
#include 
#include 
#include 

using namespace std;

int main()
{
     
    // 析构函数会调用 close
    ifstream input("test.txt");
    vector<string> vec;
    string str;

    while (input >> str)
        vec.push_back(str);

    for (auto &i : vec)
        cout << i << endl;
    
    input.close();

    return 0;
}

8.6

#include 
#include 
#include 
#include "../Sales_data/Sales_data.h"

using namespace std;

int main(int argv, char **argc)
{
     
    ifstream input(argc[1]);

    Sales_data total;

    if (read(input, total))
    {
     
        Sales_data trans;

        while (read(input, trans))
        {
     
            // 书名相同
            if (total.isbn() == trans.isbn())
            {
     
                total.combine(trans);
            }
            else // 不同输出第一个
            {
     
                print(cout, total) << endl;
                // 第二个 赋值 给 第一个
                total = trans;
            }
        }
        // 输出最后一个
        print(cout, total) << endl;
    }
    else
    {
     
        cerr << "No data?!" << endl;
        return -1;
    }

    return 0;
}

8.7

#include 
#include 
#include 
#include "../Sales_data/Sales_data.h"

using namespace std;

int main(int argv, char **argc)
{
     
    if (argv != 3)
        exit(EXIT_FAILURE);

    ifstream input(argc[1]);
    ofstream output(argc[2]);

    Sales_data total;

    if (read(input, total))
    {
     
        Sales_data trans;

        while (read(input, trans))
        {
     
            // 书名相同
            if (total.isbn() == trans.isbn())
            {
     
                total.combine(trans);
            }
            else // 不同输出第一个
            {
     
                print(output, total) << endl;
                // 第二个 赋值 给 第一个
                total = trans;
            }
        }
        // 输出最后一个
        print(output, total) << endl;
    }
    else
    {
     
        cerr << "No data?!" << endl;
        return -1;
    }

    return 0;
}

8.8

#include 
#include 
#include 
#include "../Sales_data/Sales_data.h"

using namespace std;

int main(int argv, char **argc)
{
     
    if (argv != 3)
        exit(EXIT_FAILURE);

    ifstream input(argc[1]);
    ofstream output(argc[2], ofstream::app | ofstream::out);

    Sales_data total;

    if (read(input, total))
    {
     
        Sales_data trans;

        while (read(input, trans))
        {
     
            // 书名相同
            if (total.isbn() == trans.isbn())
            {
     
                total.combine(trans);
            }
            else // 不同输出第一个
            {
     
                print(output, total) << endl;
                // 第二个 赋值 给 第一个
                total = trans;
            }
        }
        // 输出最后一个
        print(output, total) << endl;
    }
    else
    {
     
        cerr << "No data?!" << endl;
        return -1;
    }

    return 0;
}

8.9

#include 
#include 

using namespace std;

istream &print(istream &is, string &item)
{
     
    while (is >> item)
        ;
    // is.clear();

    is.clear(cin.rdstate() & ~is.failbit & ~is.eofbit);

    return is;
}

int main()
{
     
    istringstream input("hhhh hhhhh wwww wwww ffff");

    string word;
    print(input, word);

    cout << word << endl;

    return 0;
}

8.10

#include 
#include 
#include 
#include 
#include 

using namespace std;

int main()
{
     
    // 打开文件
    ifstream infile("test.txt");
    vector<string> vec;
    string str;

    // 读取文件中的一行 
    while (getline(infile, str))
        vec.push_back(str);
    
    for (decltype(vec.size()) i = 0; i < vec.size(); ++i)
    {
     
        istringstream instr(vec[i]);
        // 输出每个单词
        while (instr >> str)
            cout << str << ends;
        cout << endl;
    }

    return 0;
}

8.11

#include 
#include 
#include 
#include 
#include 

using namespace std;

struct PersonInfo {
     
    string name;
    vector<string> phones;
};

int main()
{
     
    string line, word;
    vector<PersonInfo> people;
    istringstream record;

    while (getline(cin, line))
    {
     
        PersonInfo info;
        
        record.clear(record.rdstate() & ~record.eofbit & ~record.failbit);
        record.str(line);

        record >> info.name;
        while (record >> word)
            info.phones.push_back(word);

        people.push_back(info);
    }

    for (auto &i : people)
    {
     
        cout << i.name << ends;
        for (auto &j : i.phones)
            cout << j << ends;
        cout << endl;
    }

    return 0;
}

8.12

/**
 * 没有符合的初始值
 */

8.13

#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

struct PersonInfo {
     
    string name;
    vector<string> phones;
};

bool valid(const string &s);
void enphone(ifstream &infile, vector<PersonInfo> &people);
string format(const string &s, int i);

int main(int argc, char ** argv)
{
     
    if (argc != 2)
        exit(EXIT_FAILURE);

    // 打开文件
    ifstream infile(argv[1]);
    // 电话
    vector<PersonInfo> people;

    // 输入
    enphone(infile, people);
    infile.close();
    
    // 验证
    for (const auto &entry : people)
    {
     
        // 输出
        ostringstream formatted, badNums;
        // 手机号码

        int b = 0;
        for (const auto &nums : entry.phones)
        {
     
            // 无效的
            if (!(valid(nums)))
            {
     
                badNums << " " << nums;
            }
            else // 有效的
            {
     
                formatted << " " << format(nums, ++b);
            }
        }
        // 错误号码为空
        if (badNums.str().empty())
            cout << entry.name << " "
               << formatted.str() << endl;
        else
            cerr << "input error: " << entry.name
                 << " invalid number(s) " << badNums.str() << endl;
    }

    return 0;
}

// 数字 为真
bool valid(const string &s)
{
     
    for (const auto &i : s)
        if (!isdigit(i))
            return false;

    return true;
}   

string format(const string &s, int i)
{
     
    return string("电话号码") + to_string(i) + ": " + s;
}

void enphone(ifstream &infile, vector<PersonInfo> &people)
{
     
    string str;
    while (getline(infile, str))
    {
     
        PersonInfo info;
        istringstream record(str);

        record >> info.name;
        while (record >> str)
            info.phones.push_back(str);

        people.push_back(info);
    }
}

8.14

/**
 * 没有改变数值
 */