Advanced C and C++ compiling: unable to compile the example program mentioned in the book

I'm reading the book named "Advanced C and C++ compiling", by Milan Stevanovic

The following is the snapshot from the book, followed by the problem I'm facing.

Concept illustration: Demo Project

The development environment used to build this simple project will be based on the gcc compiler running onLinux. Listings 2-1 through 2-3 contain the code used in the demo project.

Listing 2-1. function.h

#pragma once#define FIRST_OPTION#ifdef FIRST_OPTION#define MULTIPLIER (3.0)#else#define MULTIPLIER (2.0)#endiffloat add_and_multiply(float x, float y);

Listing 2-2. function.c

int nCompletionStatus = 0;float add(float x, float y){    float z = x + y;    return z;}float add_and_multiply(float x, float y){    float z = add(x,y);    z *= MULTIPLIER;    return z;}

Listing 2-3. main.c

#include "function.h"extern int nCompletionStatus = 0;int main(int argc, char* argv[]){    float x = 1.0;    float y = 5.0;    float z;    z = add_and_multiply(x,y);    nCompletionStatus = 1;    return 0;}

Demo Project Preprocessing Example:

The gcc compiler provides the mode in which only the preprocessing stage is performed on the input source files:

gcc -i <input file> -o <output preprocessed file>.i

Unless specified otherwise, the output of the preprocessor is the file that has the same name as the input file andwhose file extension is .i. The result of running the preprocessor on the file function.clooks like that in Listing 2-4.

Listing 2-4. function.i

# 1 "function.c"# 1 "# 1 "# 1 "function.h" 1# 11 "function.h"float add_and_multiply(float x, float y);# 2 "function.c" 2int nCompletionStatus = 0;float add(float x, float y){    float z = x + y;    return z;}float add_and_multiply(float x, float y){    float z = add(x,y);    z *= MULTIPLIER;    return z;}

More compact and more meaningful preprocessor output may be obtained if few extra flags are passed to the gcc, like

gcc -E -P -i <input file> -o <output preprocessed file>.i

which results in the preprocessed file seen in Listing 2-5.

Listing 2-5. function.i (Trimmed Down Version)

float add_and_multiply(float x, float y);int nCompletionStatus = 0;float add(float x, float y){    float z = x + y;    return z;}float add_and_multiply(float x, float y){    float z = add(x,y);    z *= 3.0;    return z;}

Obviously, the preprocessor replaced the symbol MULTIPLIER, whose actual value, based on the fact that theUSE_FIRST_OPTION variable was defined, ended up being 3.0.

Problem:

When I compile the program as is using gcc, following is the error I am facingSnapshot from my terminal.

gcc -i function.c -o function.icc1: error: unrecognized command line option '-i'gcc function.c -o function.i/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crt1.o:In function '_start':(.text+0x18): undefined reference to 'main'collect2: ld returned 1 exit status$pwd/home/adminuser/advance_compiling$lltotal 20drwxrwxr-x  2 adminuser adminuser 4096 Jan 10 23:51 ./drwxr-xr-x 26 adminuser adminuser 4096 Jan 10 23:57 ../-rw-rw-r--  1 adminuser adminuser  216 Nov 15 08:58 function.c-rw-rw-r--  1 adminuser adminuser  163 Jan 10 23:33 function.h-rw-rw-r--  1 adminuser adminuser  257 Dec 28 06:46 main.c

How do I get rid of this and proceed in learning the course?Please suggest.