Function Syntax Error with Modulo - c++

Question

I am confused why Visual Studios says that after century) right before the % 7; there needs to be a semicolon. It says I made a syntax error. But I want to take that whole thing in parentheses and then do the modulo 7 to it.
int determineDay(int month, int day, int year) {
const int HUNDRED_YEARS = 100;
int newYear = year % HUNDRED_YEARS;
int century = (year - newYear) / HUNDRED_YEARS;
if (month == 1) {
const int ONE_YEAR = 1;
month = 13;
year = year - ONE_YEAR;
int zellerNumber = (day + floor((13 * (month + 1)) / 5)) + year
+ floor(year / 4) + floor(century / 4) + 5 * century) % 7;
return zellerNumber;
}
else if (month == 2) {
const int ONE_YEAR = 1;
month = 14;
year = year - ONE_YEAR;
int zellerNumber = (day + floor((13 * (month + 1)) / 5)) + year
+ floor(year / 4) + floor(century / 4) + 5 * century) % 7;
return zellerNumber;
}
else {
int zellerNumber = (day + floor((13 * (month + 1)) / 5)) + year
+ floor(year / 4) + floor(century / 4) + 5 * century) % 7;
return zellerNumber;
}
}

Answer 1

As others have stated, you are missing an open parenthesis before day.
Adding to this...
This is a minor syntax error, but they will keep happening if you don't make effort to simplify your logic. Notice that the following appears in all paths of your if-else-if:
int zellerNumber = (day + floor((13 * (month + 1)) / 5)) + year
+ floor(year / 4) + floor(century / 4) + 5 * century) % 7;
Just like in math, you can "factor" this out. Since you know the logic for calculating zellerNumber is the same no matter the case (only the variables change), you can move it below your if-else-if. This also will allow you to have only one return statement. More often than not, you should aim for this.
Simplify your logic and you will see far fewer syntax errors, and the ones that you do encounter will be easier to find.