C++程序设计【九】之函数模板与类模板

深碍√TFBOYSˉ_ 2022-11-04 01:33 202阅读 0赞

> 感谢内容提供者：[金牛区吴迪软件开发工作室][Link 1]  
> 接上一篇：[C++程序设计【八】之 文件操作][C_]

### 文章目录 ###

*  第九章：函数模板与类模板
 *   *  一、函数模板
     *   *  1.函数模板的概念
         *  2.函数模板的示例
         *  3.函数或函数模板调用语句的匹配顺序
     *  二、类模板
     *   *  1.类模板概念
         *  2.类模板示例
         *  3.类模板与继承

# 第九章：函数模板与类模板 #

## 一、函数模板 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70]

### 1.函数模板的概念 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 1]

### 2.函数模板的示例 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 2]

#include<iostream>
    
    using namespace std;
    
    template<typename T>
    T abs(T x) { 
        return x < 0 ? -x : x;
    }
    
    int main() { 
        int n = -5;
        int m = 10;
        double d = -.5;
        float f = 3.2;
        cout << n << "的绝对值是：" << abs(n) << endl;
        cout << m << "的绝对值是：" << abs(m) << endl;
        cout << d << "的绝对值是：" << abs(d) << endl;
        cout << f << "的绝对值是：" << abs(f) << endl;
        return 0;
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 3]

#include<iostream>
    
    using namespace std;
    
    template<class T>
    void Swap(T &x, T &y) { 
        T tmp = x;
        x = y;
        y = tmp;
    }
    
    class myDate { 
    public:
        myDate();
        myDate(int, int, int);
        void printDate() const;
    
    private:
        int year, month, day;
    };
    myDate::myDate() { 
        year = 1970;
        month = 1;
        day = 1;
    }
    myDate::myDate(int y, int m, int d) { 
        year = y;
        month = m;
        day = d;
    }
    void myDate::printDate() const { 
        cout << year << "/" << month << "/" << day << endl;
        return;
    }
    int main() { 
        int n = 1, m = 2;
        // 编译器自动生成void Swap(int &, int &)函数
        Swap(n, m);
        cout << n << " " << m << endl;
        double f = 1.2, g = 2.3;
        // 编译器自动生成void Swap(double &, double &)函数
        Swap(f, g);
        myDate d1, d2(2000, 2, 2);  // 创建俩个对象
        // 编译器自动生成void Swap(myDate &, myDate &)函数
        Swap(d1, d2);
        d1.printDate();
        d2.printDate();
        return 0;
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 4]

#include<iostream>
    #include<string>
    
    using namespace std;
    
    template<typename T>
    int myCompare(const T &left, const T &right) { 
        if (left < right) { 
            return -1;
        } else if (right < left) { 
            return 1;
        } else { 
            return 0;
        }
    }
    template<class T>
    void Swap(T &x, T &y) { 
        T tmp = x;
        x = y;
        y = tmp;
    }
    
    int main() { 
        string arraystring[10] = { "shang", "xia", "zuo", "you", "qian", "hou", "dong", "xi", "nan", "bei"};
        int j;
        string temp;
        for (int i = 1; i < 10; i++) { 
            j = i;
            while (j > 0 && myCompare<string>(arraystring[j - 1], arraystring[j]) > 0) { 
                swap(arraystring[j], arraystring[j - 1]);
                j--;
            }
        }
        for (int i = 0; i < 10; i++) { 
            cout << arraystring[i] << ",";
        }
        return 0;
    }

### 3.函数或函数模板调用语句的匹配顺序 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 5]

## 二、类模板 ##

### 1.类模板概念 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 6]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 8]

### 2.类模板示例 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 9]

#include<iostream>
    
    using namespace std;
    
    template<class T>
    class TestClass { 
    public:
        T buffer[10];   // T类的数据成员buffer数组大小固定为10
        T getData(int j);   // 获取T类buffer（数组）的第j个分量
    };
    
    template<class T>
    T TestClass<T>::getData(int j) { 
        return *(buffer + j);
    }
    
    int main() { 
        TestClass<char> ClassInstA;  // char取代T，从而实例化为一个具体的类
        int i;
        char cArr[6] = "abcde";
        for (i = 0; i < 5; i++) { 
            ClassInstA.buffer[i] = cArr[i];
        }
        for (i = 0; i < 5; i++) { 
            char res = ClassInstA.getData(i);
            cout << res << " ";
        }
        cout << endl;
        TestClass<double> ClassInstF;    // 实例化为另外一个具体的类
        double fArr[6] = { 12.1, 23.2, 34.3, 45.4, 56.5, 67.6};
        for (i = 0; i < 6; i++) { 
            ClassInstF.buffer[i] = fArr[i] - 10;
        }
        for (i = 0; i < 6; i++) { 
            double res = ClassInstF.getData(i);
            cout << res << " ";
        }
        return 0;
    }

### 3.类模板与继承 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNjE1OA_size_16_color_FFFFFF_t_70 10]

#include<iostream>
    
    using namespace std;
    template<class T> // 类模板，基类
    class TBase { 
        T data;
    public:
        void print() { 
            cout << data << endl;
        }
    };
    class Derived:public TBase<int> { }; // 从模板继承，普通类
    
    int main() { 
        Derived d;  // 普通派生类的对象
        d.print();  // 调用类模板中的成员函数
        return 0;
    }

#include<iostream>
    
    using namespace std;
    class TBase { 
        int k;
    public:
        void print() { 
            cout << "TBase::" << k << endl;
        }
    };
    template<class T>
    class TDerived:public TBase { 
        T data;
    public:
        void setData(T x) { 
            data = x;
        }
        void print() { 
            TBase::print();
            cout << "TDerived::" << data << endl;
        }
    };
    
    int main() { 
        TDerived<string>d;
        d.setData("2019");
        d.print();
        return 0;
    }

#include<iostream>
    
    using namespace std;
    
    template<class T>
    class TBase { 
    public:
        T data1;
        void print() { 
            cout << "TBase::" << data1 << endl;
        }
    };
    
    template<class T1, class T2>
    class TDerived : public TBase<T1> { 
    public:
        T2 data2;
        void print() { 
            TBase<T1>::print();
            cout << "TDerived::" << data2 << endl;
        }
    };
    
    int main() { 
        TDerived<int, int> d;    // 类模板实例化，并声明对象
        d.data1 = 5;
        d.data2 = 8;
        d.print();
        TDerived<string, string> d2;
        d2.data1 = "happy";
        d2.data2 = "new year";
        d2.print();
        TDerived<int, string> d1;
        d1.data1 = 2021;
        d1.data2 = "good luck";
        d1.print();
        return 0;
    }

[Link 1]: http://wdstudio.top/
[C_]: https://wudi98.blog.csdn.net/article/details/114259014
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