delete.c

A simple bibliotech archive coded in C. A real exercise with fopen write and the other base functio

#include "head.h"

void  usage() {
 fprintf (stdout,"\n\nDelete program to the biblioteca.db file\n"
                 "Usage       : Required -p position -f filename\n"
                 "Flag info   : -p Position of the book\n"
                 "              -f Database file to elaborate\n\n");
 }


int  load(char *nomefile,struct libro v[])
{
 FILE *f;
 int k=0,i=0;
 if((f=fopen(nomefile,"r"))==NULL){ fprintf(stdout,"[*] I can't load the database file [*]\n");
                                    return -1;
                                  }
 while (fscanf(f,"%s%s%s%d%f\n",v[k].titolo,v[k].autori,&v[k].editore,&v[k].num_pagine,&v[k].costo) !=EOF) k++;
 fflush(f);
 fclose(f);
 return 0;
} 

int delete_mem(int position,struct libro v[])
{
bzero(v[position].titolo,MAXLENGTH);
bzero(v[position].editore,MAXLENGTH);
bzero(v[position].autori,MAXLENGTH);
v[position].costo='\0';
v[position].num_pagine='\0';
return 0;
}

int  delete(char *nome,int position) 
{
int i;
FILE *f;
if(load(nome,books)==-1) return -1;
if(delete_mem(position,books)==-1) return -1;
fprintf (stdout,"[*] Position %d ereased in memory [*]\n",position);
if((f=fopen(nome,"r+"))==NULL){ fprintf(stdout,"[*] I can't load the database file [*]\n");
                                    return -1;
                                  }
 for (i=0;i<MAX_BOOKS;i++) fprintf (f,"%s %s %s %d %f\n", books[i].titolo,books[i].autori,books[i].editore,books[i].num_pagine,books[i].costo);
fprintf (stdout,"[*] Storing your changes in your database file...[*]\n");
fclose(f);
return 0;
}

int main(int argc , char * argv[])

{
int position;
char *nomefile;
char optchar;
	if (argc<4 )
		{
		usage();
		return -1;
		}
	else 
		{
		while ((optchar=getopt(argc,argv,"p:f:"))!=EOF) 
			{
			switch(optchar) 
				{
				case 'p' :
					{	
					position=atoi(optarg);
					if (position>MAX_BOOKS || position<0)
					{
				        fprintf (stdout,"[*] The position is over the MAX position fixed (%d) if you want to change edit head.h [*]\n",MAX_BOOKS);
                                        return -1;

					}
					}
				break;
				case 'f' :

				{
				nomefile=malloc(strlen(optarg));
				strncpy(nomefile,optarg,strlen(optarg));
				}
				
				}
			}
			
	}			
if(delete(nomefile,position)==-1) return -1;
return 0;
}