C语言实例62：综合应用

//简单的通讯录程序


#include <stdio.h>
#include <stdlib.h>

#define MAX 100

struct addr
{

    char name[20];
    char street[40];
    char city[20];
    char state[4];
    unsigned long zip;
}addr_list[MAX];

void init_list(void);
void enter(void);
void dele(void);
void list(void);
void save(void);
void load(void);
int menu_select(void);
int find_free(void);

int main(int argc, char *argv[])
{
    char choice;

    init_list();

    for(;;)
    {
        choice = menu_select();

        switch(choice)
        {
            case 1:enter();
            break;

            case 2:dele();
            break;

            case 3:list();
            break;

            case 4:save();
            break;

            case 5:load();
            break;

            case 6:exit(0);
        }
    }
    system("pause");
    return 0;
}

void init_list(void)
{
    register int t;
    for(t = 0; t < MAX; t++)
        addr_list[t].name[0] = '\0';
}

void enter(void)
{
    int slot;
    char str[80];

    slot = find_free();

    if(slot == -1)
        printf("\nlist Full");

    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(str);
    addr_list[slot].zip = strtoul(str, '\0', 10);
}

void dele(void)
{
    register int slot;
    char str[80];

    printf("Enter record #:");
    gets(str);
    slot = atoi(str);

    if(slot >= 0 && slot < MAX)
        addr_list[slot].name[0] = '\0';
}

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("%s\n", addr_list[t].zip);
        }
    }

    printf("\n\n");
}

void save(void)
{
    FILE *fp;
    register int i;

    if((fp=fopen("maillist", "wb"))==NULL)
        printf("Cannot open file.\n");

    for(i=0; i<MAX; i++)
        if(*addr_list[i].name)
            if(fwrite(&addr_list[i], sizeof(struct addr), 1, fp)!=1)
                printf("File write error.\n");

    fclose(fp);
}

void load(void)
{
    FILE *fp;
    register int i;

    if((fp = fopen("maillist", "rb")) == NULL)
        printf("Cannot open file.\n");

    init_list();
    for(i = 0; i < MAX; i++)
        if(fread(&addr_list[i], sizeof(struct addr), 1, fp)!= 1)
    {
        if(feof(fp))
            break;
        printf("File read error.\n");
    }
    fclose(fp);
}


int menu_select(void)
{
    char str[80];
    int c;

    printf("1. Enter a name\n");
    printf("2. Delete a name\n");
    printf("3. list the file\n");
    printf("4. Save the file\n");
    printf("5. Load the file\n");
    printf("6. Quit\n");

    do
    {
        printf("\nEnter your choice: ");
        gets(str);
        c = atoi(str);

    }
    while(c < 0 || c > 6);

    return 0;
}

int find_free(void)
{
    register int t;
    for(t = 0; addr_list[t].name[0] && t < MAX; t++);

    if(t == MAX)
        return -1;

    return t;
}