The function "main" was defined last time. But returning 0 doesn't do very much of note. So perhaps something more interesting shall be done.
printf("Hello world.");
This shall be added to "main" right above the return 0. If you remember, return 0 exits the function, so it would
exit the function before it executed this statement here. A value enclosed in quotes here (double quotes
specifically) is a string. This is another type. Except not really, C doesn't have strings, C has char*. What
exactly that means is the next thing, it is a pointer to a char(acter), you don't need to understand that just
yet.
"printf" is a function that we are calling, you call the function by writing its name and then whatever values
it asks for in parentheses. And again, this is a statement and so it ends in a semicolon. Printf can also do
more interesting things but for now that is a later thing.
If we wanted to call "main" we would simply put:
main();But that's not a good idea. Your compiler will probably yell at you if you try that. This is just an example.