A namespace is similar to a class in object oriented programming. A namespace contains functions defined by the programmer. for example namespace std contains functions like cout and cin.
namespaces can be globaly declared like so: "using namespace std;"
which includes all the functions located in the namespace std.
if you only need to use cout you can globaly declare only cout like this "using std::cout;"
or
std::cout<<"calling cout directly from namespace std";
you can make your own namespaces as well
namespace mynamespace;
void myfunction(){
code for function
}
and use it
using mynamespace::myfunction;
The main use of a namespace is to reduce or eliminate collisions with names that may be duplicated but have different functionality. For example, I may want to use an object with the name of 'cout', but that name already exists. If I place it in a different namespace I would be able to use it with that name.
Is an important thing to do.
#include <iostream> using namespace std;
Here's one: there's no namespace in C
C++ already provides a string class in the C++ standard template library. #include<iostream> #include<string> int main() { using namespace std; string s {"Hello world!"}; cout << s << endl; }
A global object is any object instantiated in the global namespace. The global namespace is anonymous, so if we don't explicitly specify a namespace prior to instantiating an object, that object will be instantiated in the global namespace: int x; // global namespace n { int x; // non-global }; To refer to the non-global, we must use namespace resolution: x = 42; // assign to the global n::x = 42; // assign to the non-global
#include <iostream> using standard namespace std; int main() { cout << "your prob shouldn't be taking c++"; return 0; }
Is an important thing to do.
#include<iostream> int main() { using namespace std; cout<<"Hello world!"<<endl; return(0); }
If you do not include the directive using namespace stdin your program, any references to objects in namespace std will need be be qualified with that namespace. For instance...cout
#include <iostream> using namespace std;
Yes, you can program games with C++.
Here's one: there's no namespace in C
C++ already provides a string class in the C++ standard template library. #include<iostream> #include<string> int main() { using namespace std; string s {"Hello world!"}; cout << s << endl; }
A global object is any object instantiated in the global namespace. The global namespace is anonymous, so if we don't explicitly specify a namespace prior to instantiating an object, that object will be instantiated in the global namespace: int x; // global namespace n { int x; // non-global }; To refer to the non-global, we must use namespace resolution: x = 42; // assign to the global n::x = 42; // assign to the non-global
No. You can't use namespace std even if you include stdio.h. At the very least you must include stddef.h before you can use namespace std.
#include <iostream> using namespace std; int main() { for(int i = 0; i <= 100; i++) { if(i % 2 != 0) { cout << i << endl; } } char wait; cin >> wait; return 0; }
No, the use of 'namespace std' is not compulsory. You can specifiy it on any object reference. Specifying 'namespace' simply provides a default value. Contrast ... using namespace std; cout << "Hello world!" << endl; ... with ... std::cout << "Hello world!" << std::endl;