what is keyword in C++?

[mp121209]

Can you explain me what is keyword in C++? Is it a function? When I write a program like that, it works normally!
int main()

{
    int *p=new int[4];
    delete [] p;
    return 0;
}

I wonder why I didn't have to include any header file?

[kbw]

In your example, int and return are keywords.
http://en.wikipedia.org/wiki/Keyword_%28computer_programming%29

[cpluplusrat]

You did not have to include any header as you are simply not using any c++ functions. e.g, If you try to print the values in p, you will need some header.

[Bazzy]

new and delete are functions ( operators ) defined in <new> but they are treated as special cases and don't require you to #include the header
http://www.cplusplus.com/reference/std/new/