C++编程练习

题目出自《C++ Primer Plus》第5章

假设要销售《C++ For Fools》一书。请编写一个程序，输入全年中每个月的销售量（图书数量，而不是销售额)。程序通过循环，使用初始化为月份字符串的char*数组或string对象数组）逐月进行提示，并将输入的数据储存在一个int数组中。然后，程序计算数组中各元素的总数，并报告这一年的销售情况（我自定义了结构体数组一并完成第六题）。

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#include <iostream>
#include <cstdio>
const int this_year = 2017;
const int years = 3;
const int per_year = 12;
struct record
{
        int  years;
        int months;
        long sales;
};
int main()
{
        using namespace std;
        record (*date)[per_year] = new record [years][per_year];
        for (int i = 0;i < years;++i)
                for (int j = 0;j < per_year; ++j)
                {
                        date[i][j].years=this_year+i;
                        date[i][j].months=j+1;
                        cout << "Please input sales for "
                                << date[i][j].years
                                << " year "
                                << date[i][j].months
                                << " month:\n";
                        cin >> date[i][j].sales;
                }
        long long * sales_per_year = new long long [years];
        for (int i = 0;i < years; ++i)
        {
                for (int j = 0;j < per_year; ++j)
                        sales_per_year[i] += date[i][j].sales;
                cout << this_year + i 
                        << " year had been sale "
                        << sales_per_year[i]
                        << " books." << endl;
        }      
        return 0;
}

编写一个程序，它使用一个char数组和循环来每次读取一个单词，直到用户输入done为止。随后，该程序指出用户输入了多少个单词（不包括done在内）。下面是该程序的运行情况：

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Enter words (to sto p , type the word done) ：</span>
anteater birthday category dumpster
envy finagle geometry done for sure
You entered a total of 7 words.

您应在程序中包含头文件cstring,并使用函数StrCmp()来进行比较测试

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#include <iostream>
#include <cstring>
#include <stdio.h>
using namespace std;
int main()
{
    char * ch = new char;
    char * word = new char [100];
    char * string = new char [100];
    int *pcw = new int ;
    int *pcc = new int ;
    *pcc=*pcw=0;
//确认前面的一个字符不为空
    bool empty=true;
    while ( strcmp(word,"done") )
    {
        *ch=getchar();
        if ( *ch == EOF || *ch == ' ' || *ch == '\n' )
        {  
            if ( empty )
            {
                continue;
            }
            strcpy(word,string);
            string[0]='\0';
            *pcc=0;
            if ( word[0] != ' ' || word[0] != '\n' || word[0] != EOF )
                ++*pcw;
            empty=true;
            continue;
        }
        string[*pcc]=*ch;
        empty=false;
        string[(*pcc)+1]='\0';
        (*pcc)+=1;
    }
    cout << "You entered a total of "
        << (*pcw)-1
        << " words."
        << endl;
    return 0;
}

题目出自《C++ Primer Plus》第6章
编写一个程序，它毎次读取一个单词，直到用户只输入q。然后, 该程序指出有多少个单词以元音打头，有多少个单词以辅咅打头，还有多少个单词不属于这两类。为此，力法之一睡是，使用isalpha()来区分以字母和其他字符打头的单词,然后对于通过isalpha()测试的单词，使用if或switch语句来确定哪些以元音打头。该程序的运行情况如下：

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Enter words (q to quit ) :
The 12 awesome oxen ambled
quietly across 15 meters of lawn. q
5 words be ginning with vowels
4 words be ginning with consonants
2 other

*需要判断每个字符的前面一个字符和后面一个字符

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#include <iostream>
#include <cctype>
#include <cstdio>
using namespace std;
int main()
{
    cout << "Enter words (q to quit):" << endl;
    char ch;
    bool empty = true;
    int vowels,consonants,others;
    others=vowels=consonants=0;
    while ( ch = cin.get() )
    {
        cin.clear();
        if (empty)
        {
            if ( isalpha(ch) )
            {
                if ( ch == 'q' )
                {
                    char temp;
                    temp=cin.get();
                    if (temp == '\n' || temp == ' ' || temp == EOF)
                    {  
                        empty = true;
                        break;
                    }
                    else
                    {  
                        ++consonants;
                        empty = false;
                    }
                }
                else if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch =='u')
                {
                        ++vowels;
                        empty = false;
                }
                else
                {
                    ++consonants;
                    empty = false;
                }
            }
            else
            {
                ++others;
                char temp;
                if ((temp = cin.get()) != '\n' || temp != ' ' || temp != EOF)
                {
                    empty = false;
                }
                else
                {
                    empty = true;
                }
            }
        }
        else if (ch == '\n' || ch == ' ' || ch == EOF)
            empty = true;
        else
        {
            empty = false;
            continue;
        }
    }
    cout << vowels << " words beginning with vowels" << endl;
    cout << consonants << " words begining with consonants" << endl;
    cout << others << " others" << endl;
    return 0;
}

题目出自《C++ Primer Plus》第8章
函数重载(多态)，函数模板

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#include <iostream>
template <typename T> void ShowArray(T arr[],int n);
template <typename T> void ShowArray(T * arr[],int n);
int SumArray(int * ,int n);
double SumArray(double * *,int n);
struct debts
{
    char name[50];
    double amount;
};
int main()
{
    using namespace std;
    int things[6] = { 13,31,103,301,310,130 };
    struct debts mr_E[3] =
    {
        { "Ima Wolfa", 2400.0 },
        { "Ura Foxe", 1300.0 },
        { "Iby Stout", 1800.0 }
    };
    double * pd[3];
    for (int i = 0; i < 3; i++)
        pd[i] = &mr_E[i].amount;
    cout << "Listing Mr. E's counts of things:\n";
    ShowArray(things,6);
    cout << "Listing Mr. E's debts:\n";
    ShowArray(pd,3);
    cout << SumArray(things,6) << endl;
    cout << SumArray(pd,3) << endl;
    return 0;
}
template <typename T> void ShowArray(T arr [], int n)
{
    using namespace std;
    cout << "template A\n";
    for(int i = 0;i < n;i++)
        cout << arr[i] << ' ';
    cout << endl;
    return ;
}
template <typename T> void ShowArray(T * arr [] ,int n)
{
    using namespace std;
    cout << "template B\n";
    for(int i = 0;i < n;i++)
        cout << *arr[i] << ' ';
    cout << endl;
    return ;
}
int SumArray(int * arr, int n)
{
    int result = 0;
    for (int i = 0;i < n;i++)
        result +=  arr[i];
    return result;
}
double SumArray(double * * arr,int n)
{
    double result = 0;
    for(int i = 0;i < n;i++)
        result += *arr[i];
    return result;
}

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