Simple shell I worte in C

shell.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <readline/readline.h>
#include <readline/history.h>
/* to compile run gcc shell.c -o shell -Wformat-security -Wint-conversion -Wincompatible-pointer-types -lreadline */
int shell(void)
{		
		rl_bind_key('\t', rl_complete);
		const char *b[4096];
	    const char *a = gets(&b);
	    char *f = readline("shell-> ");	
	    char ex = 'exit';
	    if (f == ex ) {
	    	exit(0);
	    }   
	    const char *d = system(f);
	return(0);
}
int main(void)
{
	while(1)
		shell();
	return(0);
	if(0) {
		exit(0);
	}
}