title: Conditions in an if statement
body: <p>I'm looking through this article (<a href="https://spin.atomicobject.com/2012/06/18/solving-sudoku-in-c-with-recursive-backtracking/" rel="nofollow noreferrer">https://spin.atomicobject.com/2012/06/18/solving-sudoku-in-c-with-recursive-backtracking/</a>) explaining a backtracking approach to solve a sudoku puzzle in C and I had a couple of questions about conditions in if statements. </p>
  
  <p>He uses if(puzzle[row][column]), I am unsure as to what it is checking. If a number exists in that position it will continue? For this I would have thought to use != null to check that it's not empty</p>
  
  <p>He also uses a function call inside an if statement: if(isValid(nextNum, puzzle, row, column) Does this mean if the function is successful it executes what's inside the if?  </p>