c++ primer plus 习题答案(7)

p427.4

//头文件：
#include<iostream>
#ifndef STACK_H_
#define STACK_H_
typedef unsigned long Item;

class Stack{
private:
    enum{MAX=10};
    Item *pitems;
    int size;
    int top;
public:
    Stack(int n = 7);
    Stack(const Stack &st);
    ~Stack();
    bool isempty()const;
    bool isfull()const;
    bool push(const Item & item);
    bool pop();
    Stack & operator=(const Stack & st);
    friend std::ostream & operator<<(std::ostream & os, const Stack &st);
};

#endif

//方法：
#include<iostream>
#include<cstring>
#include"Stack.h"
using std::cout;
using std::endl;

Stack::Stack(int n){
    size = n;
    top = n;
    pitems = new Item[n];
    for (int i = 0; i < size; i++)
        pitems[i] = 0;
}

Stack::Stack(const Stack &st){
    size = st.size;
    top = st.top;
    pitems = new Item[size];
    for (int i = 0; i < size; i++)
        pitems[i] = st.pitems[i];
}

Stack::~Stack(){
    delete[]pitems;
}

bool Stack::isempty()const{
    if (top == 0)
        return true;
    else return false;
}

bool Stack::isfull()const{
    if (top == MAX)
        return true;
    else return false;
}

bool Stack::push(const Item & item){
    if (isfull()){
        cout << "the stack is already full" << endl;
        return false;
    }
    else{
        Item *temp;
        temp = new Item[size + 1];
        for (int i = 0; i < size; i++)
            *(temp + i) = *(pitems + i);
        *(temp + size) = item;
        delete[]pitems;
        pitems = temp;
        size++;
        top++;
        return true;
    }
}

bool Stack::pop(){
    if (isempty()){
        cout << "the stack is already empty" << endl;
        return false;
    }
    else{
        Item *temp;
        temp = new Item[size - 1];
        for (int i = 0; i < (size - 1); i++)
            temp[i] = pitems[i];
        delete[]pitems;
        pitems = temp;
        size--;
        top--;
        return true;
    }
}

Stack & Stack::operator=(const Stack & st){
    if (this == &st)
        return *this;
    size = st.size;
    top = st.top;
    delete[]pitems;
    pitems = new Item[st.size];
    for (int i = 0; i < size; i++)
        pitems[i] = st.pitems[i];
    return *this;
}

std::ostream & operator<<(std::ostream & os, const Stack &st){
    os << "size: " << st.size << endl
        << "top: " << st.top << endl;
    for (int i = 0; i < st.size; i++)
        os << st.pitems[i] << " ";
    return os;        
}

//驱动：
#include<iostream>
#include<cstdlib>
#include"Stack.h"
using namespace std;

int main(){
    Stack ct1;
    Stack ct2(5);
    cout << "ct1 "<< ct1 <<endl;
    cout << "ct2 "<< ct2 <<endl;
    Stack ct3 = ct2;
    cout << "ct3 "<< ct3 << endl;
    ct1 = ct2;
    cout << "ct1 " << ct1 << endl;
    ct2.push(4);
    cout << "ct2 " << ct2 << endl;
    ct1.pop();
    cout << "ct1 "<< ct1 << endl;

    system("pause");
    return 0;
}

p474.1

//头文件：
class Cd{
private:
    char performers[50];
    char label[20];
    int selections;
    double playtime;
public:
    Cd(char *s1, char *s2, int n, double x);
    Cd(const Cd & st);
    Cd();
    virtual ~Cd();
    virtual void Report()const;
    Cd & operator = (const Cd & st);
};

class Classic : public Cd
{
private:
    char production[50];
public:
    Classic(char *s1 = "nullbody1", char *s2 = "nullbody2", char *s3 = "nullbody3", int n = 0, double x = 0);
    Classic(const Classic & st);
    virtual void Report()const;
    Classic & operator=(const Classic & st);
};

//方法：
#include<iostream>
#include<cstring>
#include"classic.h"

using std::cout;
using std::endl;

Cd::Cd(char *s1, char *s2, int n, double x){
    strncpy(performers, s1, 50);
    performers[49] = '';
    strncpy(label, s2, 20);
    label[19] = '';
    selections = n;
    playtime = x;
}

Cd::Cd(const Cd & st){
    strcpy(performers, st.performers);
    strcpy(label, st.label);
    selections = st.selections;
    playtime = st.playtime;
}

Cd::Cd(){
    selections = 0;
    playtime = 0;
}

void Cd::Report()const{
    cout << "performers: " << performers << endl
        << "label: " << label << endl
        << "selections: " << selections << endl
        << "playtime: " << playtime << endl;
}

Cd & Cd::operator = (const Cd & st){
    if (this == &st)
        return *this;
    strcpy(performers, st.performers);
    strcpy(label, st.label);
    selections = st.selections;
    playtime = st.playtime;
    return *this;
}

Classic::Classic(char *s1, char *s2, char *s3, int n, double x): Cd(s2, s3, n, x){
    strncpy(production, s1, 50);
    production[49] = '';    
}

Classic::Classic(const Classic & st): Cd(st){
    strcpy(production, st.production);
}

Cd::~Cd(){

}

void Classic::Report()const{
    cout << "production: " << production << endl;
    Cd::Report();
}

Classic & Classic::operator=(const Classic & st){
    if (this == &st)
        return *this;
    Cd::operator=(st);
    strcpy(production, st.production);
    return *this;
}

//驱动：
#include<iostream>
#include<cstdlib>
using namespace std;
#include"classic.h"
void Bravo(const Cd & disk);

int main(){
    Cd c1("Beatles", "Capitol", 14, 35.5);
    Classic c2 = Classic("piano sonata in B flat", "Alfred Brendel", "Philips", 2, 57.17);
    Cd *pcd = &c1;

    cout << "using object directly
";
    c1.Report();
    c2.Report();

    cout << "using type cd *pointer to objects:
";
    pcd->Report();
    pcd = &c2;
    pcd->Report();

    cout << "calling a function with a Cd reference argument:
";
    Bravo(c1);
    Bravo(c2);
    cout << "testing assignment: ";
    Classic copy;
    copy = c2;
    copy.Report();

    system("pause");
    return 0;
}

void Bravo(const Cd & disk){
    disk.Report();
}