How to save a c++ program

Answer 1

In your computer?

1.Open Notepad++
2.Write C++ program
3.Save As. (Extension:.cpp)

Answer 2

if you are using codeblocks for example,
Go to File > New,
Type your program,
Click Save , then Save As,
Give it a name then ".cpp" extension e.g.
helloWorld.cpp
then press enter.

Answer 3

Save it as Filename.cpp