C++ different output in double and float

This question already has an answer here: What is the difference between float and double? 11 answers 33.3 has no exact bounded binary representation, so converting it to float or double incurs in rounding. float has a 23 bit mantissa, equivalent to 6.92 decimal digits of precision; there you are asking to print 8 digits, which are more than the available precision, and thus will show the

C ++在double和float中输出不同的输出

这个问题在这里已经有了答案: float和double有什么区别? 11个答案 33.3没有精确的有界二进制表示,因此将其转换为float或double float舍入。 float有一个23位的尾数,相当于精度的6.92十进制数字; 在那里你要求打印8位数字,这比可用的精度要高,因此会显示效果或四舍五入。 double代替52位尾数,相当于15.65位小数; 8位有效数字打印保持良好,因为您仍然打印好数字,不受四舍五入的影响。 为了更容易在我们心爱

Float and Double value creating confusion in c

This question already has an answer here: What is the difference between float and double? 11 answers Floating point comparison [duplicate] 5 answers Why don't you use 0.7f . 0.7 Is by default double , so we cannot predict it's behaviour

浮动和双重价值造成混乱的c

这个问题在这里已经有了答案: float和double有什么区别? 11个答案 浮点比较[复制] 5个答案 你为什么不使用0.7f 。 0.7默认情况下是double ,所以我们无法预测它的行为

Strange C++ Arduino serial behavior

I am writing some code for my arduino to print 4 button states and the X,Y coordinates from an analogue joystick and I am having strange behavior. Here is the code: int x,y; x = analogRead(joy_x); y = analogRead(joy_y); char* buf = new char[4]; sprintf(buf, "%4d", x); Serial.print("X:"); Serial.print(buf); Serial.print(" Y:"); sprintf(buf, "%4d", y); Serial.println(buf);

奇怪的C ++ Arduino串行行为

我正在为我的arduino写一些代码,以便从模拟游戏杆打印4个按钮状态和X,Y坐标,并且出现奇怪的行为。 代码如下: int x,y; x = analogRead(joy_x); y = analogRead(joy_y); char* buf = new char[4]; sprintf(buf, "%4d", x); Serial.print("X:"); Serial.print(buf); Serial.print(" Y:"); sprintf(buf, "%4d", y); Serial.println(buf); int one,two,three,four; one = digitalRead(touchOne); t

C++ “was not declared in this scope” compile error and modification tips

I'm trying to modify this code in an attempt to make it work on an Arduino Mega. I'm pretty much new to C so, I may have made some major mistakes. By the way, this is for a self balancing skateboard. :P This code is taken from an ATmega32 (from : [url=http://sites.google.com/site/onewheeledselfbalancing/Home/twin-wheel-self-balancing-skateboard-lightweight-version/code4]http://sites.

C ++“未在此范围内声明”编译错误和修改提示

我试图修改这段代码,试图让它在Arduino Mega上运行。 我对C非常陌生,所以我可能犯了一些重大错误。 顺便说一下,这是一个自平衡滑板。 :P 此代码取自ATmega32(来自:[url = http://sites.google.com/site/onewheeledselfbalancing/Home/twin-wheel-self-balancing-skateboard-lightweight-version/code4] http:// sites .google.com / site / onewheeledsel ... t-version / code4 [/ url],我试图让它在Arduino Mega

Effective C++: discouraging protected inheritance?

I was reading Scott Meyers' Effective C++ (third edition), and in a paragraph in Item 32: Make sure public inheritance is "is-a" on page 151 he makes the comment (which I've put in bold): This is true only for public inheritance. C++ will behave as I've described only if Student is publicly derived from Person. Private inheritance means something entirely different (see

有效的C ++:不鼓励受保护的继承?

我正在阅读Scott Meyers的Effective C ++ (第三版),并且在第32项的一段中:确保公共继承是“is-a”(第151页),他发表了评论(我用粗体表示): 这只适用于公共继承。 只有当Student是从Person公开派生时,C ++才会像我所描述的那样工作。 私有继承意味着完全不同的东西(参见条款39), 并且受保护的继承是其含义直到今天都没有意义的东西。 问题 :我应该如何解释这个评论? 梅尔斯是否试图传达那种被保护的遗传很少

Use of "Public" in a derived class declaration?

Given this base class: class Employee { char* name; int age; public: Employee(char* name); void print(); }; With regards to the "public", what's the difference between this: class Manager : public Employee { EmployeeList employees; public: Manager(char* name, Employee* people); void print(); }; and this: class Manager : Employee { Empl

在派生类声明中使用“Public”?

鉴于这个基类: class Employee { char* name; int age; public: Employee(char* name); void print(); }; 关于“公众”,这有什么区别: class Manager : public Employee { EmployeeList employees; public: Manager(char* name, Employee* people); void print(); }; 和这个: class Manager : Employee { EmployeeList employees; public: Manager(char* name, Employ

Why sub class manage to access c++ private inheritance member?

This question already has an answer here: Difference between private, public, and protected inheritance 15 answers When you private inherit from a base class, its public members become private members of the derived class. These members are public and accessible inside of member functions of the derived class (eg B.getmultiply() ), but are private and not accessible to outside code (eg main(

为什么子类管理访问c ++私有继承成员?

这个问题在这里已经有了答案: 私人,公共和受保护遗产之间的区别15个答案 当您从基类继承私有成员时,其公共成员将成为派生类的私有成员。 这些成员是公共的,并且可以在派生类的成员函数内部访问(例如B.getmultiply() ),但是是私有的,并且不是派生类的朋友的外部代码(例如main() )不可访问的成员函数。 当一个类私下继承另一个类时,它仍然可以访问该类的(非私有)成员,就像在公共继承下一样。 只有外部世界没

Protected Inheritance in C++

This question already has an answer here: Difference between private, public, and protected inheritance 15 answers With protected inheritance inherited public members become protected . With private inheritance inherited public and protected members become private .

C ++中的受保护继承

这个问题在这里已经有了答案: 私人,公共和受保护遗产之间的区别15个答案 随着protected继承继承public成员protected 。 随着private继承继承public和protected成员变得private 。

How does inheritance actually work?

This question already has an answer here: Difference between private, public, and protected inheritance 15 answers First bullet point you are right. The derived class object, has a region called the "base class sub-object". Thus the derived class object contains a base class subobject in precisely the same way that it contains member subobjects for any non-static data members. (T

继承如何实际工作?

这个问题在这里已经有了答案: 私人,公共和受保护遗产之间的区别15个答案 第一个要点是你是对的。 派生类对象有一个称为“基类子对象”的区域。 因此,派生类对象包含一个基类子对象,其方式与包含任何非静态数据成员的成员子对象的方式完全相同。 (尽管这并不总是如此,因为编译器试图优化事物,并且最终的对象可能没有为非常简单的示例明确区分成员变量)。 第二点你错了。 它们都指向A :: a_p(属于A类的属性)。

Variable inaccessible despite class inheritance?

This question already has an answer here: Difference between private, public, and protected inheritance 15 answers private variables are not accessible by derived classes. If you want to have access to it, you'll need to declare it as protected . Also, your Truck class should declare a virutal destructor if you plan to use it as a polymorphic base class.

尽管类继承,变量不可访问?

这个问题在这里已经有了答案: 私人,公共和受保护遗产之间的区别15个答案 private变量不能被派生类访问。 如果你想访问它,你需要声明它是protected 。 此外,如果您打算将它用作多态基类,则您的Truck类应该声明一个virutal析构函数。