How can I split up my monolithic programs into smaller, separate files?

Question

In all the code I see online, programs are always broken up into many smaller files. For all of my projects for school though, I\'ve gotten by by just having one gigantic C sour

Answer 1

Just to give you an idea.

create a file called print.c, put this inside:

#include 
#include 
#include 

void print_on_stdout(const char *msg) {
   if (msg) fprintf(stdout, "%s\n", msg);
}
void print_on_stderr(const char *msg) {
   if (msg) fprintf(stderr, "%s\n", msg);
}

create a file called print.h, put this inside:

void print_on_stdout(const char *msg);
void print_on_stderr(const char *msg);

create a file called main.c, put this inside:

#include 
#include 
#include 

#include "print.h"

int main() {
    print_on_stdout("test on stdout");
    print_on_stderr("test on stderr");

    return 0;
}

Now, for each C file, compile with:

gcc -Wall -O2 -o print.o -c print.c
gcc -Wall -O2 -o main.o -c main.c

Then link compiled files to generate an executable:

gcc -Wall -O2 -o test print.o main.o

Run ./test and enjoy.