whats a cout?

[jadedman]

do you know whats a cout?
what are its function and in what library can it be found?

It's a C++ standard predefined output stream (see http://www.cplusplus.com/reference/iostream/cout.html)

[William Hemsworth]

GIYF! http://www.google.co.uk/search?hl=en&q=C%2B%2B+cout+stream&btnG=Search&meta=

[jadedman]

so a cout needs the three header files to be in effect...

[Ancient Dragon]

so a cout needs the three header files to be in effect...

NO. cout only needs <iostream>

#include <iostrem>
using std::cout;

int main()
{
    cout << "Hello World\n";
    return 0;
}

[jadedman]

after the #include<iostream>, there's a statement,
"using std::cout;", what is it function?

[Ancient Dragon]

Read about namespaces here and here.

[x3mario]

cout is an object of class ostream that represents the standard output stream. It corresponds to the cstdio stream stdout.
By default, most systems have their standard output set to the console, where text messages are shown, although this can generally be redirected.
Because cout is an object of class ostream, we can write characters to it either as formatted data using for example the insertion operator (ostream::operator<<) or as unformatted data using the write member function, among others (see ostream).