PE 14-1
 
/* pe14-1.c  */
#include <stdio.h>
#include <string.h>
#include <ctype.h>
 
struct month {
    char name[10];
    char abbrev[4];
    int days;
    int monumb;
};
 
const struct month months[12] = {
    {"January", "Jan", 31, 1},
    {"February", "Feb", 28, 2},
    {"March", "Mar", 31, 3},
    {"April", "Apr", 30, 4},
    {"May", "May", 31, 5},
    {"June", "Jun", 30, 6},
    {"July", "Jul", 31, 7},
    {"August", "Aug", 31, 8},
    {"September", "Sep", 30, 9},
    {"October", "Oct", 31, 10},
    {"November", "Nov", 30, 11},
    {"December", "Dec", 31, 12}
};
 
int days(char * m);
int main(void)
{
    char input[20];
    int daytotal;
 
    printf("Enter the name of a month: ");
    while (gets(input) != NULL && input[0] != '\0')
    {
        daytotal = days(input);
        if (daytotal > 0)
            printf("There are %d days through %s.\n", daytotal, input);
        else
            printf("%s is not valid input.\n", input);
        printf("Next month (empty line to quit): ");
    }
    puts("bye");
    
    return 0;
}
 
int days(char * m)
{
    int total = 0;
    int mon_num = 0;
    int i;
    if (m[0] == '\0')
        total = -1;
    else
    {
        m[0] = toupper(m[0]);
        for (i = 1; m[i] != '\0'; i++)
            m[i] = tolower(m[i]);
        for (i = 0; i < 12; i++)
            if (strcmp(m, months[i].name) == 0)
            {
                mon_num = months[i].monumb;
                break;
            }
        if (mon_num == 0)
            total = -1;
        else
            for (i = 0; i < mon_num; i++)
                total +=months[i].days;
    }
    return total;
}