doomsday calc

#define Sunday 0
#define Monday 1
#define Tuesday 2
#define Wednesday 3
#define Thursday 4
#define Friday 5
#define Saturday 6
#define GREG_CAL 1582

int anchorDay(int yearEntered){
    int day;
    if(yearEntered>2100){
        day = 0;
    }
    if(yearEntered<2099){
        day = 2;
    }
    if(yearEntered<1999){
        day = 3;
    }
    if(yearEntered<1899){
        day = 5;
    }
    return day;
}

int findDoomsday(int returnedAnchorDay, int enteredYear){

    int result;
    int intermediateres = enteredYear;
    int divcounter;
    int intermediateresdiv;
    int resdiff;
    int divcounttwelve;
    int divbyfour;
    int divbyfourcount;
    int divsevencount;

//Determines the last two digits of the number
    while(intermediateres>1000){
        intermediateres = intermediateres - 1000;
    }

//Stores the last two digits into another variable for use
    intermediateresdiv = intermediateres

//Determines the mod12 of the last two digits of the year
    //Without using mod
    while(intermediateres >12){
        intermediateres= intermediateres - 12;
        divcounter += 1;
    }

//Determines the difference between the generated number and
    //the last two digits of the year
    divcounttwelve = divcounter * 12;
    resdiff = intermediateres - divcounttwelve

//Divide resdiff by 4 and gain the whole number resul
    divbyfour = resdiff
    while(divbyfour>4){
        divbyfour - 4;
        divbyfourcount += 1;
    }

//Add all the results together
    result = divcounter + divcounttwelve + divbyfourcount + returnedAnchorDay;

//Mod 7
    while(result>7){
        result = result - 7;
        divsevencount += 1;
    }

//Returns the day that the doomsday falls on
    return divsevencount;


}

int isLeapYear (int yearvar)

{
    int success = 0;

    if ((yearvar % 100)==0) {
        success = 0;
    }

    if ((yearvar % 4)==0) {
        success = 1;
    }

    if ((yearvar % 400)==0) {
        success = 1;
    }
    return success;
}

int dayOfWeek (int doomsday, int leapYear, int month, int day) {
   int dayOfWeek;



   return (dayOfWeek);

int main (int argc, const char * argv[]){
    int userYearInput;
    int returnedanchorday = anchorDay(userYearInput);
    int yeardoomsday = findDoomsday(returnedanchorday, userYearInput);
    int leapYear = isLeapYear(userYearInput);

}