Answer to Exercise 1-1, page 8 Linguaggio C

Run the "hello, world" program on your system. Experiment with leaving out parts of the program, to see what error messages you get.

Murphy's Law dictates that there is no single correct answer to the very first exercise in the book. Oh well. Here's a "hello world" program:

#include <stdio.h>

int main(void)
{
  printf("hello, world\n");
  return 0;
}

As you can see, I've added a return statement, because main always returns int, and it's good style to show this explicitly.
Here's a list of simple compile lines for a variety of popular compilers:

GNU C
gcc -W -Wall -ansi -pedantic -o hello hello.c

Microsoft C, up to version 5.1
cl -W3 -Zi -Od -AL hello.c

Microsoft C,version 6, Microsoft Visual C++ 1.0, 1.5
cl -W4 -Zi -Od -AL hello.c

Microsoft Visual C++ 2.0 and later
cl -W4 -Zi -Od hello.c

Turbo C++
tcc -A -ml hello.c (I think)

Borland C++, 16 bit versions
bcc -A -ml hello.c

Borland C++, 32 bit versions
bcc32 -A hello.c