高级C和C++编译：无法编译书中提到的示例程序

Question

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 on Linux. 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)
#endif

float 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 and whose file extension is .i . The result of running the preprocessor on the file function.c looks 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" 2
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;
}

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 the USE_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 facing Snapshot from my terminal.

gcc -i function.c -o function.i
cc1: 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
$ll
total 20
drwxrwxr-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.

Answer 1

-i is not a valid command line option - I'm not sure where the book got it from. In order to just run the preprocessor, you should use the option -E instead.

Answer 2

I was a technical reviewer of the book and the author asked me to post this explanation on his behalf:

The error you found is indeed an error, introduced in the very late stage of book proofreading/editing. Sorry for stepping on it + for book errata still not being printed out (will happen some time soon).

Answer 3

Try this

gcc -E -P function.c -o function.i

without the -i option, it's not a gcc option.

note : this answer was fixed after I realized that have misunderstood the question, so i fixed to keep it and not delete it, but Katie did answer it before I did.

Answer 4

Judging by the .i output file in the book's example, it seems the error is in the utility itself.

Instead of using gcc , use cpp . gcc uses cpp (The C Preprocessor) under the hood to handle macro expansion and header inclusion. The output of cpp is a .i file for c source code and .ii for c++.

cpp function.c > function.i

Answer 5

Try the following code:

function.c

#include "function.h"
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;
}

main.c

    //#include "function.h"
    extern int nCompletionStatus;
    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;
    }

Now execute:
gcc function.c main.c

otherwise 
gcc -c function.c
gcc function.o main.c