参考资料: http://www.programlife.net/union-struct-in-c.html http://blog.csdn.net/huqinwei987/article/details/23597091 本文参与 腾讯云自媒体同步曝光计划,分享自作者个人站点/博客。 原始发表:2015-07-20 ,如有侵权请联系 cloudcommunity@tencent.com 删除 前往查看 http 编程算法 ...
If I were writing this program, I'd prefer to write a main like this: int main(int argc, char *argv[]) { if (argc < 2) { std::cout << "Too few arguments.\n"; return -1; } auto size = std::atoi(argv[1]); Percolation p(size); std::cout << "System percolates at " ...
A C/C++ union. See C.8.2. For example, the typeMyUnionin: union MyUnion {int i;float f;}; Import path import cpp Indirect supertypes @declaration @element @namequalifyingelement @type @usertype AccessHolder Class Declaration Element
The union is at least as big as necessary to hold its largest data member, but is usually not larger. The other data members are intended to be allocated in the same bytes as part of that largest member. The details of that allocation are implementation-defined, except that all non-static...
If a union of two types is declared and one value is stored, but the union is accessed with the other type, the results are unreliable. For example, a union offloatandintis declared. Afloatvalue is stored, but the program later accesses the value as anint. In such a situation, the ...
extern keyword in C extern 可以告诉编译器,在编译单元的某处,有这么一个全局变量。 int i; 是变量的定义 extern int i; 是变量的声明,所以,extern 不能初始化变量。 声明和定义 声明不产生代码 函数原型 变量、结构、宏、枚举、类型声明 inline函数 ...
For example, a union of float and int is declared. A float value is stored, but the program later accesses the value as an int. In such a situation, the value would depend on the internal storage of float values. The integer value would not be reliable.Examples...
(with the issuance of a diagnostic message). Many incorrect program constructs do not engender undefined behavior; they are required to be diagnosed. Evaluation of a constant expression ([expr.const]) never exhibits behavior explicitly specified as undefined in [intro] through [cpp]. — end note...
prompt>g++ -std=c++98 -Wall -I../include -o 01-basic.exe 01-basic.cpp && 01-basic.exe In a nutshell variant liteis a single-file header-only library to represent a type-safe union. The library aims to provide aC++17-like variantfor use with C++98 and later. If available, std::...
Ifsizeof...(Types)==0or if any of the types inTypesis not a complete object type, the behavior is undefined. It is implementation-defined whether anyextended alignmentis supported. If the program adds specializations forstd::aligned_union, the behavior is undefined. ...