using namespace std; class A {}; class A2 {char d,e;}; struct B{}; struct C{ char x,y;}; struct D{int x,y;}; main() { cout< cout< A. *p1=new A(); B. p2; 相关知识点: 试题来源: 解析 对于一个类而言,即便它是一个空的类,编译器仍然要要给它一个空间,所以类A即便什么...
using std::cin; using std::cout; using std::endl; using std::runtime_error; int main(void){ for (int i, j;cin >> i >> j; ){ try { if (j == 0) throw runtime_error("divisor is 0"); cout << i / j << endl;} ...
what is the output the following code?#include using namespace std;class A1 { public: int a; static int b;A1(); ~A1();}; 4class A2 { public: int a; char c; A2(); ~A2();}; 8class A3 { public: float a; char c; A3(); ~A3();}; 8class A4 { public: float a; int...
using namespace std let u access to standard library in cpp such string or vector , if u dont , for example to use tge cout , u have to access to it using :: , std::cout , so to make it simple , u use std namespace and just call cout 24th Nov 2017, 8:16 AM Maher Zaido...
usingnamespacestd;tell the compiler "take everything that's in the std namespace and dump it in the global namespace". This allows you to usecoutwithout the std:: prefix, but it increases the probability for name conflicts, since a bunch of extra names that you didn't expect also got...
it stops you from having to type std:: before everything for example std::cout << "Hello World"; becomes cout << "Hello World"; I do also believe you cxan use it for other things like in Visual C++ when you generate a form it does some using namespace system; or something similar...
world [root@iZuf62soquu9rssso122mlZ test]# cat test1.cpp #include<iostream> #include<stdexcept> using namespace std; char *strcpy(char* dest, const char *src){ if(dest==src) return dest; if((dest==NULL)||(src==NULL)) return NULL; ...
To get direct access to variables and methods defined in the standard libraries that come in C++... cout and cin are a good example of this...if you don't declare "using namespace std" at the begining of your code then you will have to use std::cout and std::cin each time you ...
And just what is "namespace"? Is it also some kind of library? Or is it something that is built in to C++? Or what? Oh, and what does "std" mean or stand for? I like to understand these things. usingnamespacestd; Last edited onSep 11, 2014 at 1:40am ...
usingnamespacestd; template<typenameTP> structCOne {// default member is public typedefTP one_value_type; }; template<typenameCOne>// 用一个模板类作为模板参数, 这是很常见的 structCTwo { // 请注意以下两行 // typedef COne::one_value_type two_value_type; // *1 ...