Printing calendar for specific year and month - c

Question

I am trying to print out a calendar for a specific year and month but keep getting the same calendar for every month. I tried to also add a statement to see if the year is a leap year to add to the number of days but it made no difference. I am new to c.Please help with any suggestions. Thanks in advance.
void print_month_calendar(int year, int month)
{
int day;
int daycode = ddaycode(year);
int days_in_month[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
char *months[]=
{
" ",
"\n\n\nJanuary",
"\n\n\nFebruary",
"\n\n\nMarch",
"\n\n\nApril",
"\n\n\nMay",
"\n\n\nJune",
"\n\n\nJuly",
"\n\n\nAugust",
"\n\n\nSeptember",
"\n\n\nOctober",
"\n\n\nNovember",
"\n\n\nDecember"
};
printf("%s", months[month]);
printf("\n\nSun Mon Tue Wed Thu Fri Sat\n");
if(( year%4==0 && year%100 !=0) || year%400==0)
days_in_month[2] = 29;
for (day = 1; day <= 1 + daycode * 5; day++)
{
printf(" ");
}
//Print all the dates for the month
for (day = 1; day <= days_in_month[month]; day++)
{
printf("%2d", day);
if ((day + daycode) % 7 > 0)
printf(" ");
else
printf("\n ");
}
}
int ddaycode(int year)
{
int daycode;
int d1, d2, d3;
d1 = (year - 1.)/ 4.0;
d2 = (year - 1.)/ 100.;
d3 = (year - 1.)/ 400.;
daycode = (year + d1 - d2 + d3) %7;
return daycode;
}

Answer 1

You have to know the first weekday in the month. You can use localtime to go to specific date, use mktime to get struct tm data which contains weekday. In addition, you can use strftime to get the month name. Example:
void print_month_calendar(int year, int month)
{
time_t rawtime;
struct tm * timeinfo;
time(&rawtime);
timeinfo = localtime(&rawtime);
timeinfo->tm_year = year - 1900;
timeinfo->tm_mon = month - 1;
timeinfo->tm_mday = 1;
mktime(timeinfo);
//sunday is 1 ... saturday is 7
int weekday = 1 + timeinfo->tm_wday;
int days_in_month[] = { 0, 31,28,31,30,31,30,31,31,30,31,30,31 };
if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0))
days_in_month[2]++;
char monthname[30];
strftime(monthname, sizeof(monthname), "%B", timeinfo);
printf(" %s %d\n", monthname, year);
printf(" Su Mo Tu We Th Fr Sa\n");
int day = 1;
for (int i = 1; i <= 40; i++)
{
if (i < weekday)
{
printf(" ");
}
else
{
printf("%3d ", day);
if (day == days_in_month[month])
break;
day++;
if ((i % 7) == 0)
printf("\n");
}
}
printf("\n");
}
int main()
{
print_month_calendar(2016, 10);
return 0;
}
ideone example
October 2016
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31