Copy the code from text file to command prompt

I don't really understand what it is you're asking. Do you want to output the source code to the terminal? Can't you just use the "cat" command for this? For example, if your program was called "foo", you could run it and then print the source code with

$ ./foo; cat foo.c

Note the semi-colon separating the two command lines. Is this what you want? If not, can you give a more detailed explanation please?

If you just want to copy and paste you can use gnome terminal in linux or putty in windows, both support copy/paste to and from a command line.

$ cat hello.c
foo()
{
printf "Hello World";
}

$ gcc hello.c

this code may help you to write and compile c program in Linux command prompt.