第八章 編程練習

編程練習1

#include <iostream>
using namespace std;

void p(char  ch[]);
void p(char  ch[], int i);
const int ChSize = 40;

int main()
{
    char ch[ChSize];
    cout << "please enter a string: ";
    cin.getline(ch, ChSize);
    p(ch);
    p(ch, 5);
    system("pause");
    return 0;
}

void p(char  ch[])
{
    cout <<"show this string only once: "<<endl;
    cout << ch <<endl;
}
void p(char ch[], int i)
{
    if (i!=0)
    {
        cout <<"show this string " <<i<<" time(s): "<<endl;
        for (int n=0;n<=i;n++)
        cout << ch << endl;
    }
}

編程練習2

#include <iostream>
using namespace std;

struct CandyBar{
    char name[40];
    double weight;
    int kcal;
};

void set(CandyBar &cb,const char name[] = "Millennium Munch",const double weight=2.85,const int kcal=350);
void show(const CandyBar &cb);

int main(){
    CandyBar cb,cb2;

    set(cb, "candy12345",123.2, 1700);
    set(cb2);

    show(cb);
    show(cb2);

    system("pause");
    return 0;
}

void set(CandyBar &cb,const char name[],const double weight,const int kcal){
    strcpy(cb.name, name);
    cb.weight = weight;
    cb.kcal = kcal;
}
void show(const CandyBar &cb){
    using namespace std;
    std::cout << "name: "<< cb.name << ", weight: "<<cb.weight<<", kcal: "<<cb.kcal<<std::endl;
}

編程練習3

#include <iostream>
#include <string>
using namespace std;

string toupper(string str);

int main()
{
    string str;
    while(true)
    {
        cout<< "Enter a string (q to quite): ";
        getline(cin,str);
        if(str=="q")
            break;
        cout << toupper(str) <<endl;
    }

    system("pause");
    return 0;
}

string toupper(string str)
{
    for (int i=0;i<str.length();i++)
    {
        str[i] = toupper(str[i]);
    }
    return str;
}

編程練習4

#include <iostream>
#include <string>
using namespace std;

struct stringy {
    char * str;
    int ct;
};
void set(stringy &sty, const char * st);
void show(const stringy &sty, int i=1);
void show(const string &str, int i=1);
int main()
{
    stringy beany;
    char testing[] = "Reality isn't what it used to be.";

    set(beany, testing);
    show(beany);
    show(beany, 2);
    testing[0] = 'D';
    testing[1] = 'u';
    show(testing);
    show(testing, 3);
    show("Done!");

    system("pause");
    return 0;
}
void set(stringy &sty, const char * st)
{
    char * cs = new char[strlen(st)+1];
    strcpy(cs, st);
    sty.str = cs;;
    sty.ct = strlen(st);
}
void show(const stringy &sty, int i)
{
    for (i; i>0;i--)
    {
        cout << "string is: " << sty.str << endl;
        cout << "string length is: " << sty.ct << endl;
    }

}
void show(const string &str, int i)
{
    for (i; i>0;i--)
    {
        cout << "string is: " << str << endl;
    }

}

編程練習5

#include <iostream>

using namespace std;

template <class T>
T max5(T *t);

int main()
{
    int intArray[5] = {1,4,8,12,3};
    double doubleArray[5] = {3.2, 5.67, 9.0, 12.5, 3.19};
    cout << max5(intArray) << endl;
    cout << max5(doubleArray) << endl;
    system("pause");
    return 0;
}
template <class T>
T max5(T *t)
{
    T temp = *t;
    for (int i=1;i<5;i++)
    {
        t++;
        if (temp<*t)
        temp=*t;
    }
    return temp;
}

編程練習6

#include <iostream>
#include <cstring>
using namespace std;

template <typename T>
T maxn(T arr[], int n);

template <> char * maxn<char *>(char *arr[], int n);



int main()
{
    int intarr[6] = {1, 2, 3, 4, 5, 6};
    double doublearr[4] = {1.2, 3.4, 4.5, 5.6};
    char *charr[5]={"wang","li","zhang","zhao","huang"};

    cout << " the largest integer is : " << maxn(intarr, 6) << endl;
    cout << " the largest double is : " << maxn(doublearr, 6) << endl;
    cout << " the longest string is : " << maxn(charr, 5) << endl;
    system("pause");
    return 0;
}
template <typename T>
T maxn(T arr[], int n)
{
    T temp = arr[0];
    for (int i = 1; i < n; i++)
    {
        if (temp < arr[i])
            temp = arr[i];
    }
    return temp;
}

template <> char * maxn<char *>(char *arr[], int n)
{
    char *pa=arr[0];
    int temp = strlen(pa);
    for (int i = 1; i < n; i++)
    {
        if(temp < strlen(arr[i]))
            pa = arr[i];
        else 
            pa = pa;
    }
    return pa;
}

編程練習7

#include <iostream>

using namespace std;

template <typename T>
void ShowArray(T arr[], int n);

template <typename T>
void ShowArray(T * arr[], int n);

template <typename T>
void SumArray(T arr[], int n);

template <typename T>
void SumArray(T * arr[], int n);


struct debts
{
    char name[30];
    double amount;
};

int main()
{
    int things[6] = {13, 31, 103, 301, 310, 130};
    struct debts mr_E[3] = 
    {
        {"Ima Wolfe", 2400},
        {"Ura Foxe", 1300},
        {"Iby Stout", 1800}
    };
    double *pd[3];

    for (int i=0; i<3;i++)
        pd[i] = &mr_E[i].amount;

    cout << "Listing Mr. E's counts of things: "<<endl;
    ShowArray(things, 6);
    SumArray(things, 6);
    cout <<"Listing Mr. E's debts: "<<endl;
    ShowArray(pd, 3);
    SumArray(pd, 3);

    system("pause");
    return 0;
}
template <typename T>
void ShowArray(T arr[], int n)
{
    cout << "template A"<<endl;
    for (int i=0;i<n;i++)
        cout << arr[i]<<" ";
    cout<<endl;
}

template <typename T>
void ShowArray(T * arr[], int n)
{
    cout << "template B"<<endl;
    for (int i=0;i<n;i++)
        cout << *arr[i]<<" ";
    cout<<endl;
}

template <typename T>
void SumArray(T arr[], int n)
{
    cout << "template C"<<endl;
    T temp = 0;
    for (int i=0;i<n;i++)
        temp = temp+arr[i];
    cout<<"sum of array is " << temp <<endl;
}

template <typename T>
void SumArray(T * arr[], int n)
{
    cout << "template D"<<endl;
    T temp = 0;
    for (int i=0;i<n;i++)
        temp = temp+ *arr[i];
    cout<<"sum of array is " << temp <<endl;
}