Consecutive months (enum & struct) C

#include <stdio.h>

typedef enum month {jan,feb,mar,apr,may,jun,jul,aug,sep,oct,nov,dec} month;
typedef struct date {month mth; int day;} date;

int last, con;

void today (date* pass)
{
    switch (pass->mth)
    {
        case jan: printf("January %d", pass->day); 
        break;
        
        case feb: printf("February %d", pass->day);
        break;
        
        case mar: printf("March %d", pass->day);
        break;
        
        case apr: printf("April %d", pass->day);
        break;
        
        case may: printf("May %d", pass->day);
        break;
        
        case jun: printf("June %d", pass->day);
        break;
        
        case jul: printf("July %d", pass->day);
        break;
        
        case aug: printf("August %d", pass->day);
        break;
        
        case sep: printf("September %d", pass->day);
        break;
        
        case oct: printf("October %d", pass->day);
        break;
        
        case nov: printf("November %d", pass->day);
        break;
        
        case dec: printf("December %d", pass->day);
        break;
        
     }
    
}
date*tomorrow(date*pass)
{
    if(pass->day==last)
    {
        pass->day=(pass->day+1)%last;
        pass->mth=(pass->mth+1)%12;
    }
    else 
    
    pass->day=pass->day+1;
    return 0;
}
int main()
{
    date first_date={jan, 1};
    date second_date={feb, 28};
    date third_date={mar,14};
    date fourth_date={oct, 31};
    date fifth_date={dec, 1};
    
    date dates[]={first_date, second_date, third_date, fourth_date, fifth_date};
    
    for(con=0; con<5;con++)
    {
        printf("the date is");
        today(&dates[con]);
        
        printf("\n the next day is");
        tomorrow(&dates[con]);
        today(&dates[con]);
        
    }
    return 0;
}