A simple mailing list example using an array of structures
/*
C: The Complete Reference, 4th Ed. (Paperback)
by Herbert Schildt
ISBN: 0072121246
Publisher: McGraw-Hill Osborne Media; 4 edition (April 26, 2000)
*/
/* A simple mailing list example using an array of structures. */
#include <stdio.h>
#include <stdlib.h>
#define MAX 100
struct addr {
char name[30];
char street[40];
char city[20];
char state[3];
unsigned long int zip;
} addr_list[MAX];
void init_list(void), enter(void);
void delete(void), list(void);
int menu_select(void), find_free(void);
int main(void)
{
char choice;
init_list(); /* initialize the structure array */
for(;;) {
choice = menu_select();
switch(choice) {
case 1: enter();
break;
case 2: delete();
break;
case 3: list();
break;
case 4: exit(0);
}
}
return 0;
}
/* Initialize the list. */
void init_list(void)
{
register int t;
for(t=0; t<MAX; ++t) addr_list[t].name[0] = '\0';
}
/* Get a menu selection. */
int menu_select(void)
{
char s[80];
int c;
printf("1. Enter a name\n");
printf("2. Delete a name\n");
printf("3. List the file\n");
printf("4. Quit\n");
do {
printf("\nEnter your choice: ");
gets(s);
c = atoi(s);
} while(c<0 || c>4);
return c;
}
/* Input addresses into the list. */
void enter(void)
{
int slot;
char s[80];
slot = find_free();
if(slot==-1) {
printf("\nList Full");
return;
}
printf("Enter name: ");
gets(addr_list[slot].name);
printf("Enter street: ");
gets(addr_list[slot].street);
printf("Enter city: ");
gets(addr_list[slot].city);
printf("Enter state: ");
gets(addr_list[slot].state);
printf("Enter zip: ");
gets(s);
addr_list[slot].zip = strtoul(s, '\0', 10);
}
/* Find an unused structure. */
int find_free(void)
{
register int t;
for(t=0; addr_list[t].name[0] && t<MAX; ++t) ;
if(t==MAX) return -1; /* no slots free */
return t;
}
/* Delete an address. */
void delete(void)
{
register int slot;
char s[80];
printf("enter record #: ");
gets(s);
slot = atoi(s);
if(slot>=0 && slot < MAX)
addr_list[slot].name[0] = '\0';
}
/* Display the list on the screen. */
void list(void)
{
register int t;
for(t=0; t<MAX; ++t) {
if(addr_list[t].name[0]) {
printf("%s\n", addr_list[t].name);
printf("%s\n", addr_list[t].street);
printf("%s\n", addr_list[t].city);
printf("%s\n", addr_list[t].state);
printf("%lu\n\n", addr_list[t].zip);
}
}
printf("\n\n");
}
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