C++字符串比较的问题

[a17050243]

/*1．为CPublication 类定义小于运算符(‘<’)运算符重载函数。CPublication类对象大小的比较是根据其标题(p_title)的字符串的大小
来实现的。（提示：使用strcmp()字符串比较库函数）
2．修改CPublication类派生的CBook和CJournal两个类(CBook类增加作者，页数，出版社三个数据成员以及相应的构造，析购，
设置和打印成员函数。CJournal增加主办单位一个数据成员以及相应的构造，析购，设置和打印成员函数。)，
对这两个类都进行赋值运算符重载和增加拷贝构造函数。
（如果有必要，可以对基类数据成员访问属性进行相应修改）
3．写主函数对新增功能进行测试。*/
#include <iostream>
#include <string.h>
#include <iomanip>
using namespace std;

class CPublication
{
protected:
    char *p_title;
    float price;
    char *p_date;
    bool on_loan;
public:
    CPublication(const char *p_t, float p, const char *p_d)
    {
        p_title = new char [strlen(p_t) + 1];
        strcpy (p_title,p_t);
        price = p;
        p_date = new char [strlen(p_d) + 1];
        strcpy (p_date,p_d);
        on_loan = true;
    }
    CPublication(const CPublication& c)
    {
        p_title = new char [strlen(c.p_title) + 1];
        strcpy (p_title,c.p_title);
        price = c.price;
        p_date = new char [strlen(c.p_date)+1];
        strcpy (p_date,c.p_date);
        on_loan = true;
    }
    void set(const char *p_t, float p, const char *p_d)
    {
        price = p;
        delete [] p_title;
        p_title = new char [strlen(p_t)+1];
        strcpy (p_title,p_t);
        delete [] p_date;
        p_date = new char [strlen(p_d)+1];
        strcpy (p_date,p_d);
        on_loan = true;
    }
    bool borrowIt()
    {
        if(on_loan == true)
        {
            on_loan = false;
            return true;
        }
        else
        {
            cout << "该书已借出！" << endl;
            return false;
        }
    }
    bool returnIt()
    {
        on_loan = true;
        return true;
    }
    void print() const
    {
        cout << "书名：" << p_title << endl;
        cout << setiosflags(ios::fixed) << setprecision(2) << "价格：" << price << endl;
        cout << "出版日期：" << p_date << endl;
        if(on_loan == true)
            cout << "可借出" << endl;
        else
            cout << "已借出" << endl;
    }
    friend bool operator < (const CPublication &c, const CPublication &d);
    virtual ~CPublication()
    {
        delete [] p_title;
        delete [] p_date;
    }
};

bool operator < (const CPublication &c, const CPublication &d)
    {
        if(strcmp(c.p_title,d.p_title) < 0)
            return true;
        else
            return false;
    }

class CBook : public CPublication
{
protected:
    char *b_author;
    int pages;
    char *b_press;
public:
    CBook(const char *p_t, float p, const char *p_d, const char *b_a, int ps, const char *b_p):CPublication(p_t,p,p_d)
    {
        b_author = new char [strlen(b_a) + 1];
        strcpy (b_author,b_a);
        pages = ps;
        b_press = new char [strlen(b_p) + 1];
        strcpy (b_press,b_p);
    }
    CBook(const CBook &c):CPublication(c)
    {
        pages = c.pages;
        delete [] b_author;
        b_author = new char [strlen(c.b_author) + 1];
        strcpy (b_author,c.b_author);
        delete [] b_press;
        b_press = new char [strlen(c.b_press) + 1];
        strcpy (b_press,c.b_press);
    }
    void set(const char *b_a, int ps, const char *b_p)
    {
        pages = ps;
        delete [] b_author;
        b_author = new char [strlen(b_a) + 1];
        strcpy (b_author,b_a);
        delete [] b_press;
        b_press = new char [strlen(b_p) + 1];
        strcpy (b_press,b_p);
    }
    void print() const
    {
        cout << "书名：" << p_title << endl;
        cout << setiosflags(ios::fixed) << setprecision(2) << "价格：" << price << endl;
        cout << "出版日期：" << p_date << endl;
        cout << "作者：" << b_author << endl;
        cout << "页数：" << pages << endl;
        cout << "出版社：" << b_press << endl;
        if(on_loan == true)
            cout << "可借出" << endl;
        else
            cout << "已借出" << endl;
    }
    friend bool operator < (CBook &c, CBook &d);
    ~CBook()
    {
        delete [] b_author;
        delete [] b_press;
    }
};

bool operator < (CBook &c, CBook &d)
    {
        if(strcmp(c.b_author,d.b_author) < 0)
            return true;
        else
            return false;
    }

class CJournal : public CPublication
{
protected:
    char *j_host;
public:
    CJournal(const char *p_t, float p, const char *p_d, const char *j_h):CPublication(p_t,p,p_d)
    {

        j_host = new char [strlen(j_h) + 1];
        strcpy (j_host,j_h);
    }
    CJournal(const CJournal &c):CPublication(c)
    {
        delete [] j_host;
        j_host = new char [strlen(c.j_host) + 1];
        strcpy (j_host,c.j_host);
    }
    void set(const char *j_h)
    {
        delete [] j_host;
        j_host = new char [strlen(j_h) + 1];
        strcpy (j_host,j_h);
    }
    void print() const
    {
        cout << "书名：" << p_title << endl;
        cout << setiosflags(ios::fixed) << setprecision(2) << "价格：" << price << endl;
        cout << "出版日期：" << p_date << endl;
        cout << "主办单位：" << j_host << endl;
        if(on_loan == true)
            cout << "可借出" << endl;
        else
            cout << "已借出" << endl;

    }
    friend bool operator < (CJournal &c, CJournal &d);
    ~CJournal()
    {
        delete [] j_host;
    }
};

bool operator < (CJournal &c, CJournal &d)
    {
        if(strcmp(c.j_host,d.j_host) < 0)
            return true;
        else
            return false;
    }

int main()
{
    CPublication book("面向对象程序设计C++语言编程",32.00,"2008.1");
    book.borrowIt();
    book.returnIt();
    book.print();

    CPublication bookk("模拟电子技术",25.00,"2008.7");
    bookk.borrowIt();
    bookk.returnIt();
    bookk.print();

    if(book < bookk)
        cout << ">>>>>>>book's title is less than bookk's title" << endl;
    else
        cout << ">>>>>>>book's title is longer than(equal) bookk's title" << endl;
    cout << "----------------------------------------------------------------------------" << endl;

    CBook bbook("数字电路与逻辑设计",21.00,"2006.11","蔡良伟",260,"西安电子科技大学出版社");
    bbook.print();

    CBook bbookk("数据结构(C语言版)",22.00,"2008.3","严蔚敏|吴伟民",335,"清华大学出版社");
    bbookk.print();

    if(bbook < bbookk)
        cout << ">>>>>>>bbook's author is less than bbookk's author" << endl;
    else
        cout << ">>>>>>>bbook's author is longer than(equal) bbookk's author" << endl;
    cout << "----------------------------------------------------------------------------" << endl;

    CJournal jbook("概率论与数理统计",19.30,"2008.4","浙江大学");
    jbook.print();

    CJournal jbookk("物理学下册",31.00,"2007.12","东南大学");
    jbookk.print();

    if(jbook < jbookk)
        cout << ">>>>>>>jbook's host is less than jbookk's host" << endl;
    else
        cout << ">>>>>>>jbook's host is longer than(equal) jbookk's host" << endl;

    return 0;
}

编译的时候没有出错
但是到了执行的时候，程序并不能正确的判断出字符串的大小（例如主函数里面，“面向对象程序设计C++语言编程”比“模拟电子技术”大，可是程序却一直显示的是“book's title is less than bookk's title”）
现在要怎么修正？

可能表达的不清晰~见谅~

[fice1989]

没错啊 ，“面向对象程序设计C++语言编程”本来就比“模拟电子技术”小啊

不知道你是用的什么编译器，我的是vs2008
其对中文字符的大小比较其实就是按拼音来的
像你这个里面的例子
a=“mian xiang dui xiang ...”
b=“mo ni dian zhi ...”

比较方式：
a[0] == b[0]
所以继续比较下一位
a[1] < b[1]

所以返回的是a < b
你的结果显示是正确的！

[a17050243]

是这样进行比较的啊...

那请问怎么比较他们之间的长度呢？

[猫已经找不回了]

mi<mo

[lylm]

同意1楼

[lylm]

[Quote=引用 2 楼 a17050243 的回复:]
是这样进行比较的啊...

那请问怎么比较他们之间的长度呢？
[/Quote]
strlen，汉字2个字节

[a17050243]

谢谢楼上几位！

那么在注释中的“CPublication类对象大小的比较是根据其标题(p_title)的字符串的大小来实现的。（提示：使用strcmp()字符串比较库函数）”是什么意思呢？

[fice1989]

字符串的比较跟字符串的长度是没有关系的，就是对位比较
汉字是比较拼音序列
英文字母就是直接比较对应位置上的字符的值
第一个大的整个字符串就是大的

还有建议你在c++中对字符串的处理多用string类型
安全性比较高
而且也很方便

[a17050243]

原来是这样，非常感谢各位^_^