Printing a calendar with month and year in C - c

Question

I'm trying to make a program that will print out the month from the given year and month that the user inputs. What I have so far just ends up printing out the entire calendar year.
#include<stdio.h>
int determineleapyear(int 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"
};
int determinedaycode(int year)
{
int d1, d2, d3;
d1 = year/4.0;
d2 = year/100.;
d3 = year/400.;
return 1 + (year + d1 + d2 + d3 + 1) % 7;
}
int determineleapyear(int year)
{
return (year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0));
}
void calendar(int year, int month, int daycode)
{
int day;
printf("%s", months[month]);
printf("\n\nSun Mon Tue Wed Thu Fri Sat\n");
//Correct the position for the first date
for (day = 1; day <= 1 + daycode * 5; day++)
{
printf(" ");
}
//Print all the dates for one month
for (day = 1; day <= days_in_month[month]; day++)
{
printf("%2d", day);
//Is day before Sat? Else start next line Sun.
if ((day + daycode) % 7 > 0)
printf(" ");
else
printf("\n ");
}
// Set position for next month
daycode = (daycode + days_in_month[month]) % 7;
if (determineleapyear(year))
days_in_month[2] = 29;
printf("\n %s %d\n", months[month], year);
}
//------------------------------------------
int main() {
int daycode, month, year;
printf("\nEnter the month: ");
scanf("%d", &month);
if (month < 1 || month > 12)
{
printf("Error: month must be in range 1..12");
return printf("\nEnter the month: ");
scanf("%d", &month);
}
printf("\nEnter the year: ");
scanf("%d", &year);
if (year < 0)
{
printf("Error: year must be > 0");
return scanf("%d", &year);
}
daycode = determinedaycode(year);
calendar(year, month, daycode);
printf("\n");
return 0;
}
Can anyone help me out with making it print just one month?

Answer 1

Your calendar function is running a loop from 1 to 12, which is causing all months to be printed. Remove the loop and replace it with a parameter to allow the user to select a month:
void calendar(int year, int month, int daycode)
{
int day;
printf("%s", months[month]);
printf("\n\nSun Mon Tue Wed Thu Fri Sat\n");
//Correct the position for the first date
for (day = 1; day <= 1 + daycode * 5; day++)
{
printf(" ");
}
//Print all the dates for one month
for (day = 1; day <= days_in_month[month]; day++)
{
printf("%2d", day);
//Is day before Sat? Else start next line Sun.
if ((day + daycode) % 7 > 0)
printf(" ");
else
printf("\n ");
}
// Set position for next month
daycode = (daycode + days_in_month[month]) % 7;
}
Call it in main using the variable read from input:
calendar(year, month, daycode);
I would also highly recommend validating input. Something like the following:
printf("\nEnter the month: ");
scanf("%d", &month);
if (month < 1 || month > 12)
{
printf("Invalid month selected");
return -1;
}