pe12_2.cpp

我学习C++ Primer Plus过程中写下的课后作业的编程代码

/*
2. 通过完成下面的工作来改进String类声明(即将String1.h升级为String2.h):
a.对+操作符进行重载,使之可将两个字符串合并成1个.
b.提供一个Stringlow()成员函数,将字符串中所胡的字母字符转换为小写.
c.提供一个Stringup()成员函数,将字符串中所有字母字符转换为大写.
d.提供一个这样的成员函数,它接受一个char参数,返回该字符在字符串中出现的次数.
使用下面的pe12_2.cpp程序来测试您的工作:
Your output should look like this sample run:

Please enter your name: Fretta Farbo
My name is Fretta Farbo.
The string
MY NAME IS FRETTA FARBO AND I AM A C++ STUDENT.
contains 6 'A' characters in it.
Enter the name of a primary color for mixing light: yellow
Try again!
BLUE
That's right!
Bye

*/

// pe12_2.cpp
#include <iostream>
using namespace std;
#include "String2.h"
int main()
{
    String s1(" and I am a C++ student.");
    String s2 = "Please enter your name: ";
    String s3;
    cout << s2;                 // overloaded << operator
    cin >> s3;                  // overloaded >> operator
    s2 = "My name is " + s3;    // overloaded =, + operators
    cout << s2 << ".\n";
    s2 = s2 + s1;
    s2.stringup();              // converts string to uppercase
    cout << "The string\n" << s2 << "\ncontains " << s2.has('A')
            << " 'A' characters in it.\n";
    s1 = "red";     // String(const char *),
                    // then String & operator=(const String&)
    String rgb[3] = { String(s1), String("green"), String("blue")} ;
    cout << "Enter the name of a primary color for mixing light: ";
    String ans;
    bool success = false;
    while (cin >> ans)
    {
        ans.stringlow();        // converts string to lowercase
        for (int i = 0; i < 3; i++)
        {
            if (ans == rgb[i])  // overloaded == operator
            {
                cout << "That's right!\n";
                success = true;
                break;
            }
        }
        if (success)
            break;
        else
            cout << "Try again!\n";
    }
    cout << "Bye\n";
    return 0;
}