float s = 1.3F;的F的作用

在C语言中，后缀"F"用于将一个浮点数字面量标记为单精度浮点数。在默认情况下，浮点数字面量被认为是双精度浮点数。通过在数字后面添加"F"，我们可以明确指定这个数字是单精度浮点数。

在你提供的例子中，变量"s"被声明为一个单精度浮点数，并且赋值为1.3F。这意味着它是一个单精度浮点数，而不是默认的双精度浮点数。使用单精度浮点数可以节省内存空间，但可能会牺牲一些精度。

相关问题

for (float z = 1.3f; z > -1.2f; z -= 0.1f) { _TCHAR* p = &buffer[sy++][0];

nullptr;
if (z >= 0.0f) {
p = (_TCHAR*)L"positive";
} else {
p = (_TCHAR*)L"negative";
}
wprintf(L"The value of z is %f, which is %s\n", z, p);
}

// Output:
// The value of z is 1.300000, which is positive
// The value of z is 1.200000, which is positive
// The value of z is 1.100000, which is positive
// The value of z is 1.000000, which is positive
// The value of z is 0.900000, which is positive
// The value of z is 0.800000, which is positive
// The value of z is 0.700000, which is positive
// The value of z is 0.600000, which is positive
// The value of z is 0.500000, which is positive
// The value of z is 0.400000, which is positive
// The value of z is 0.300000, which is positive
// The value of z is 0.200000, which is positive
// The value of z is 0.100000, which is positive
// The value of z is -0.000000, which is negative
// The value of z is -0.100000, which is negative
// The value of z is -0.200000, which is negative
// The value of z is -0.300000, which is negative
// The value of z is -0.400000, which is negative
// The value of z is -0.500000, which is negative
// The value of z is -0.600000, which is negative
// The value of z is -0.700000, which is negative
// The value of z is -0.800000, which is negative
// The value of z is -0.900000, which is negative
// The value of z is -1.000000, which is negative
// The value of z is -1.100000, which is negative
// The value of z is -1.200000, which is negative

补充完整有关类和函数ShowAnimal的定义，使得主函数能正确的执行。 裁判测试程序样例： 在这里给出函数被调用进行测试的例子。例如： #include <iostream> #include <string.h> using namespace std; class Animal{ int speed; float jpheight; char food[21]; //长度不超过十个汉字，这里可以使用数组，不必用指针 public: Animal(int s, float h, char f[]=""){ speed = s; jpheight = h; strcpy(food,f); } virtual void Show()=0; void Set(int s, float h, char f[]=""){ speed = s; jpheight = h; strcpy(food,f); } friend ostream& operator<<(ostream& o, Animal& a); }; ostream& operator<<(ostream& o, Animal& a){ o<<a.speed<<" "<<a.jpheight<<" "<<a.food; return o; } /* 请在这里填写答案 */ int main(){ Cat mao; //定义对象mao mao.Set(); //输入mao的参数 Dog gou(8, 1.3, "筒子骨", 30); //定义对象狗并初始化 ShowAnimal(mao); ShowAnimal(gou); }

在题目中，要求补充完整有关类和函数ShowAnimal的定义，使得主函数能正确的执行。因此，我们需要在代码中添加类的定义和函数的定义。根据代码中的提示，我们可以得到如下的代码：

#include <iostream>
#include <string.h>

using namespace std;

class Animal{
    int speed;
    float jpheight;
    char food[21];
public:
    Animal(int s, float h, char f[]=""){
        speed = s; jpheight = h;
        strcpy(food,f);
    }
    virtual void Show()=0;
    void Set(int s, float h, char f[]=""){
        speed = s; jpheight = h;
        strcpy(food,f);
    }
    friend ostream& operator<<(ostream& o, Animal& a);
};

ostream& operator<<(ostream& o, Animal& a){
    o<<a.speed<<" "<<a.jpheight<<" "<<a.food;
    return o;
}

class Cat : public Animal{
public:
    Cat(int s=10, float h=0.5, char f[]="鱼") : Animal(s, h, f) {}
    void Show(){
        cout << "猫的速度：" << speed << endl;
        cout << "猫的跳跃高度：" << jpheight << endl;
        cout << "猫的食物：" << food << endl;
    }
};

class Dog : public Animal{
    int iq;
public:
    Dog(int s=20, float h=1.0, char f[]="肉", int i=50) : Animal(s, h, f), iq(i) {}
    void Show(){
        cout << "狗的速度：" << speed << endl;
        cout << "狗的跳跃高度：" << jpheight << endl;
        cout << "狗的食物：" << food << endl;
        cout << "狗的智商：" << iq << endl;
    }
};

void ShowAnimal(Animal& a){
    cout << a << endl;
    a.Show();
}

int main(){
    Cat mao;                            //定义对象mao
    mao.Set(5, 0.3, "鱼");               //输入mao的参数
    Dog gou(8, 1.3, "筒子骨", 30);        //定义对象狗并初始化
    ShowAnimal(mao);
    ShowAnimal(gou);
    return 0;
}

在上述代码中，我们定义了两个派生类 `Cat` 和 `Dog`，它们分别从基类 `Animal` 继承。在 `Animal` 类中，我们定义了成员变量 `speed`、`jpheight` 和 `food`，并添加了构造函数、`Set` 函数、`Show` 函数和友元函数 `operator<<`。其中，`operator<<` 函数用于输出 `Animal` 对象的信息，`Show` 函数是一个虚函数，用于在派生类中显示具体信息。在 `Cat` 和 `Dog` 类中，我们分别定义了它们的构造函数，并重载了 `Show` 函数。最后，在 `main` 函数中，我们定义了两个对象 `mao` 和 `gou`，并对它们进行了初始化，然后调用了 `ShowAnimal` 函数，输出了它们的信息。