引入两个同名的枚举项的两个usingenum声明会冲突。 enumclassfruit{orange, apple};enumclasscolor{red, orange};voidf(){usingenumfruit;// OK// using enum color; // 错误:color::orange 与 fruit::orange 冲突} (C++20 起) 注解 无作用域枚举类型的值可以被提升或转换为整数类型: ...
enum class color { red, orange, yellow }; struct highlight { using enum color; }; (C++20 起)局部类类声明可以在函数体内出现,此时它定义局部类。这种类的名字只存在于函数作用域中,且无法在函数外访问。 局部类的成员只能在该类的定义中声明,除了嵌套类成员也可以在该类的最近外围块作用域中声明。
one ofenum,enum class, orenum struct (since C++11) attr-(since C++11)optional sequence of any number ofattributes enum-head-name- the name of the enumeration that's being declared, it can be omitted. (until C++11) the name of the enumeration that's being declared, optionally preceded by...
enumclasserrc; (since C++11) The scoped enumerationstd::errcdefines the values of portable error conditions that correspond to the POSIX error codes. Member constants NameEquivalent POSIX Error address_family_not_supportedEAFNOSUPPORT address_in_useEADDRINUSE ...
break语句只能跳出本层循环,假如你要跳出一个三重嵌套的循环,你就要使用包含其它的逻辑或者用一个goto语句跳出这个嵌套循环. case 在switch里面用来检测匹配 . default,switch catch catch 语句通常通过throw语句捕获一个异常. 这一页... class class-name : inheritance-list { ...
区别4,struct/class/enum/enum class, 在讲述之前,我先提醒一下大家在C++中, struct 和 class 对编译器看来,只有默认的成员变量作用域不同,一个是public,另一个是private,然后其他没有区别;推荐一个知乎不错的回答 c++为什么要让struct可以定义成员函数?,我引用一下里面的一些精华内容,从3点概括C++编译器可以做...
{union{inta;constchar*p; }; a=1; p="Jennifer"; } union-like class #include<iostream>//S has one non-static data member (tag), three enumerator members,//and three variant members (c, n, d)structS {enum{CHAR, INT, DOUBLE} tag;union{charc;intn;doubled; ...
class ostrstream : public std::ostream (obsoleta) O ostrstream classe implementa operações de saída de matriz lastreados córregos. É essencialmente envolve uma matriz-prima I / implementação do dispositivo O (std::strstreambuf) para a interface de nível superior de std::basic...
> class basic_stringstream; (até C++11) template< class CharT, class Traits = std::char_traits<CharT>, class Allocator = std::allocator<CharT> > class basic_stringstream; (desde C++11) O modelo de classe implementa basic_stringstream de entrada / saída operações em memória (...
int x = static_cast<int>(President::MCKINLEY); // can specify any integer data type as the underlying type enum class Day : char {MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY}; 6. Templates 6.1. Function Templates template <class T> void swap(T &i, T &j) { T temp = i; i = ...