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Simple database: Difference between revisions
→{{header|C}}: Solve in C
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See also [[Take notes on the command line]] for a related task.
=={{header|C}}==
A simple database in C with some error checking, even. A quick test with Valgrind revealed no obvious memory leaks. The following data was used for testing. -> database.csv
"Soon Rising","Dee","Lesace","10-12-2000","New Hat Press"
"Brave Chicken","Tang","Owe","04-01-2008","Nowhere Press"
"Aardvark Point","Dee","Lesace","5-24-2001","New Hat Press"
"Bat Whisperer, The","Tang","Owe","01-03-2004","Nowhere Press"
"Treasure Beach","Argus","Jemky","09-22-1999","Lancast"
<lang C>#include <stdio.h>
#include <stdlib.h> /* malloc */
#include <string.h> /* strlen */
#define _XOPEN_SOURCE /* requred for time functions */
#define __USE_XOPEN
#include <time.h>
#define DB "database.csv" /* database name */
#define TRY(a) if (!(a)) {perror(#a);exit(1);}
#define TRY2(a) if((a)<0) {perror(#a);exit(1);}
#define FREE(a) if(a) {free(a);a=NULL;}
#define sort_by(foo) \
static int by_##foo (pdb_t *p1, pdb_t *p2) { \
return strcmp ((*p1)->foo, (*p2)->foo); }
typedef struct db {
char title[26];
char first_name[26];
char last_name[26];
time_t date;
char publ[100];
struct db *next;
}
db_t,*pdb_t;
typedef int (sort)(pdb_t*, pdb_t*);
typedef int (*compfn)(const void*, const void*);
enum {CREATE,PRINT,TITLE,DATE,AUTH,READLINE,READ,SORT,DESTROY};
static pdb_t dao (int cmd, FILE *f, pdb_t db, sort sortby);
static char *time2str (time_t *time);
static time_t str2time (char *date);
/* qsort callbacks */
sort_by(last_name);
sort_by(title);
static sort by_date;
/* main */
int main (int argc, char **argv) {
char buf[100], *commands[]={"-c", "-p", "-t", "-d", "-a", NULL};
db_t db;
db.next=NULL;
pdb_t dblist;
int i;
FILE *f;
TRY (f=fopen(DB,"a+"));
if (argc<2) {
usage: printf ("Usage: %s [commands]\n"
"-c Create new entry.\n"
"-p Print the latest entry.\n"
"-t Print all entries sorted by title.\n"
"-d Print all entries sorted by date.\n"
"-a Print all entries sorted by author.\n",argv[0]);
fclose (f);
return 0;
}
for (i=0;commands[i]&&strcmp(argv[1],commands[i]);i++);
switch (i) {
case CREATE:
printf("-c Create a new entry.\n");
printf("Title :");if((scanf(" %25[^\n]",db.title ))<0)break;
printf("Author Firstname:");if((scanf(" %25[^\n]",db.first_name))<0)break;
printf("Author Lastname :");if((scanf(" %25[^\n]",db.last_name ))<0)break;
printf("Date 10-12-2000 :");if((scanf(" %10[^\n]",buf ))<0)break;
printf("Publication :");if((scanf(" %99[^\n]",db.publ ))<0)break;
db.date=str2time (buf);
dao (CREATE,f,&db,NULL);
break;
case PRINT:
printf ("-p Print the latest entry.\n");
while (!feof(f)) dao (READLINE,f,&db,NULL);
dao (PRINT,f,&db,NULL);
break;
case TITLE:
printf ("-t Print all entries sorted by title.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,by_title);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
case DATE:
printf ("-d Print all entries sorted by date.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,by_date);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
case AUTH:
printf ("-a Print all entries sorted by author.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,by_last_name);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
default: {
printf ("Unknown command: %s.\n",strlen(argv[1])<10?argv[1]:"");
goto usage;
} }
fclose (f);
return 0;
}
/* Data Access Object (DAO) */
static pdb_t dao (int cmd, FILE *f, pdb_t in_db, sort sortby) {
pdb_t *pdb=NULL,rec=NULL,hd=NULL;
int i=0,ret;
char buf[100];
switch (cmd) {
case CREATE:
fprintf (f,"\"%s\",",in_db->title);
fprintf (f,"\"%s\",",in_db->first_name);
fprintf (f,"\"%s\",",in_db->last_name);
fprintf (f,"\"%s\",",time2str(&in_db->date));
fprintf (f,"\"%s\" \n",in_db->publ);
break;
case PRINT:
for (;in_db;i++) {
printf ("Title : %s\n", in_db->title);
printf ("Author : %s %s\n", in_db->first_name, in_db->last_name);
printf ("Date : %s\n", time2str(&in_db->date));
printf ("Publication : %s\n\n", in_db->publ);
if (!((i+1)%3)) {
printf ("Press Enter to continue.\n");
ret = scanf ("%*[^\n]");
if (ret<0) return rec; /* handle EOF */
else getchar();
}
in_db=in_db->next;
}
break;
case READLINE:
if((fscanf(f," \"%[^\"]\",",in_db->title ))<0)break;
if((fscanf(f," \"%[^\"]\",",in_db->first_name))<0)break;
if((fscanf(f," \"%[^\"]\",",in_db->last_name ))<0)break;
if((fscanf(f," \"%[^\"]\",",buf ))<0)break;
if((fscanf(f," \"%[^\"]\" ",in_db->publ ))<0)break;
in_db->date=str2time (buf);
break;
case READ:
while (!feof(f)) {
dao (READLINE,f,in_db,NULL);
TRY (rec=malloc(sizeof(db_t)));
*rec=*in_db; /* copy contents */
rec->next=hd;/* to linked list */
hd=rec;i++;
}
if (i<2) {
puts ("Empty database. Please create some entries.");
fclose (f);
exit (0);
}
break;
case SORT:
rec=in_db;
for (;in_db;i++) in_db=in_db->next;
TRY (pdb=malloc(i*sizeof(pdb_t)));
in_db=rec;
for (i=0;in_db;i++) {
pdb[i]=in_db;
in_db=in_db->next;
}
qsort (pdb,i,sizeof in_db,(compfn)sortby);
pdb[i-=1]->next=NULL;
for (;i;i--) {
pdb[i-1]->next=pdb[i];
}
rec=pdb[0];
FREE (pdb);
pdb=NULL;
break;
case DESTROY: {
while ((rec=in_db)) {
in_db=in_db->next;
FREE (rec);
} } }
return rec;
}
/* convert numeric time to date string */
static char *time2str (time_t *time) {
static char buf[255];
struct tm *ptm;
ptm=localtime (time);
strftime(buf, 255, "%m-%d-%Y", ptm);
return buf;
}
/* convert date string to numeric time */
static time_t str2time (char *date) {
struct tm tm;
memset (&tm, 0, sizeof(struct tm));
strptime(date, "%m-%d-%Y", &tm);
return mktime(&tm);
}
/* sort by date callback for qsort */
static int by_date (pdb_t *p1, pdb_t *p2) {
if ((*p1)->date < (*p2)->date) {
return -1;
}
else return ((*p1)->date > (*p2)->date);
}</lang>
=={{header|Common Lisp}}==
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