Matrix Checking Rows

[hockeynl]

I have to create a program that allows a user to fill in a (partial) Latin Square of order 4. You can use 0's to represent empty cells. The user will give the number to place, the row and column. The number should only be placed if it does not violate the properties of a partial Latin Square and it shouldn't rewrite numbers that have already been placed.

I am now checking the rows to see if a number is allowed in that row (that number is not present in that row)

My code: https://gist.github.com/anonymous/a8c0dcc070df2b35c31b

I am not sure what to put in my for loop or if statement. I do now that I have to loop through the columns.