C++ 函数模板、类模板

函数模板

#include <iostream>
using namespace std;

template <class T>
T abs(T x) {
    return x < 0 ? -x : x;
}
// ---
//多个参数相同
template <typename T>
void Swap(T &x, T &y) {
    T tmp = x;
    x = y;
    y = tmp;
}

class myDate {
public:
    myDate();
    myDate(int month, int day);
    void printDate() const;
private:
    int month, day;
};
myDate::myDate() {
    month = 5;
    day = 20;
}
myDate::myDate(int m, int d) {
    month = m;
    day = d;
}
void myDate::printDate() const {
    cout<<month<<" "<<day<<endl;
}
// ---
//多个参数不同
template <class T1, class T2>
void print(T1 m, T2 n) {
    cout<<m<<" "<<n<<endl;
}

int main(int argc, const char * argv[]) {
    
    cout<<abs(-5.00324)<<endl;
    
    int m = 1, n = 2;
    Swap(m, n);
    cout<<m<<"-"<<n<<endl;
    
    myDate d1, d2(6, 30);
    swap(d1, d2);
    d1.printDate();
    d2.printDate();
    
    print<int, double>(5, 5.8198);
    
    return 0;
}

类模板

#include <iostream>
using namespace std;

template <typename T>
class TestClass {
public:
    T buffer[11];
    T getData(int j);
};
template <typename T>
T TestClass<T>::getData(int j) {
    return *(buffer + j);
};

// ---
template <int i>
class TestClass2 {
public:
    int buffer[11];
    int getData(int j);
};
template <int i>
int TestClass2<i>::getData(int j) {
    return *(buffer + j);
}

// --- 继承
template <typename T>
class Tbase {
    T data;
public:
    void print() { }
};
class Derived: public Tbase<int> { };

class Tbase2 {
    int i;
public:
    void print() { cout<<i<<endl; }
};
template <typename T>
class Derived2: public Tbase2 {
    T data;
public:
    void setData(T x) {
        data = x;
    }
    void print() {
        Tbase2::print();
        cout<<data<<endl;
    }
};

template <class T>
class Father {
    T data;
public:
    void print() { cout<<data<<endl; }
};
template <class T1, class T2>
class Son: Father<T1> {
    T2 data2;
public:
    void print() { cout<<data2<<endl; }
};

int main(int argc, const char * argv[]) {
    
    TestClass<char> c;
    char cArr[6] = "abcd";
    for (int i = 0; i < 5; i ++) {
        c.buffer[i] = cArr[i];
    }
    for (int i = 0; i < 5; i ++) {
        char res = c.getData(i);
        cout<<res<<" ";
    }
    cout<<endl;
    
    TestClass<double> d;
    double dArr[6] = {12.35, 23.23, 56.8, 26.9, 62.6, 21.5};
    for (int i = 0; i < 6; i ++) {
        d.buffer[i] = dArr[i] - 10;
    }
    for (int i = 0; i < 6; i ++) {
        double res = d.getData(i);
        cout<<res<<" ";
    }
    cout<<endl;
    
    TestClass2<7> t;
    double dArr2[7] = {12.35, 23.23, 56.8, 26.9, 62.6, 21.5, 123.13};
    for (int i = 0; i < 7; i ++) {
        t.buffer[i] = dArr2[i] - 10;
    }
    for (int i = 0; i < 7; i ++) {
        double res = t.getData(i);
        cout<<res<<" ";
    }
    cout<<endl;
    
    Derived2<string> d2;
    d2.setData("2020");
    d2.print();
    
    Son<int, int> s;
    s.print();
    Son<string, string> s2;
    s2.print();
    
    return 0;
}