You need to #include the header file that contains the missing function's declaration.
it is sqrt in header math.h
conio.h is a library function which is predefined in the header file and 'clrscr();','getch();' and many other functions come under this.
That means, the header of a function. The header is the top part, before the opening braces.
Java does not require header files like C/C++.
No predefined 'header' function in the standard C libraries. There are header files, if that's what you mean.
No explicit limit, you can use so many header files as you want.
Yes.
The sequence number, acknowledge number, and Window fields.
The std::pow() function can be found in the <cmath> header.
Frame Header - Network Header - Transport Header - Data - Frame Trailer
A haeder is a text-file, meant to include (#include) into a source-file. Usually it contains variable and function declarations, constants, type-definitions, documentation.
Header files are used to have declarations. It is simple to include a single header file than writing all the needed functions prototypes.