I need help understanding julian dates.
I am trying to create a program using julian dates where user enters month & year and show the calendar of that month.
I especially don't understand the "int toJulian()"...

here is what I have so far:

``````#include <stdio.h>
#define START 1900 //fixed year

//PROTOTYPES here

void main(void)
{
int day, month, year, startDay, numDays;
numDays = 0;
startDay = 1;
day = 0;
getMonthYear(&month, &year);
toJulian(month, day, year);
yearsToDays(year);
printCalendar(startDay, numDays);
}
void getMonthYear(int *month, int *year)
{
printf("Enter month: ");
scanf_s("%d", month);
printf("Enter year: ");
scanf_s("%d", year);
printf("\n");

}
int toJulian(int month, int day, int year) //takes calendar date and calculates its julian day within the year
{
int count;
for(count = 1; count < month; ++count)
day =+ daysInMonth(month, year);

}
int daysInMonth(int month, int year) //takes a month and year and calculates how many days are in this particular month
{
int numDays;
if (month == 1)
numDays = 31;
else if (month == 2)
numDays = 28 + leapYear(year);
else if (month == 3)
numDays = 31;
else if (month == 4)
numDays = 30;
else if (month == 5)
numDays = 31;
else if (month == 6)
numDays = 30;
else if (month == 7)
numDays = 31;
else if (month == 8)
numDays = 31;
else if (month == 9)
numDays = 30;
else if (month == 10)
numDays = 31;
else if (month == 11)
numDays = 30;
else if (month == 12)
numDays = 31;
}
int leapYear(int year) //takes year and returns 1 if leap year otherwise 0
{
if (year % 400 == 0)
return 1;
else
return 0;
}
long yearsToDays(int year) // takes year returns the number of days from 1/1/1900 to end of previous year.
{
int count;
long days;
for(count = START; count < year; ++count)
days = 365 + leapYear(year);
}
void printCalendar(int startDay, int numDays)
{
int num, dayid;