Common Mistakes

Using = instead of == in if satements. Remember that = is the assignment operator, and is used to assign values to variables. == is the equality operator, and is used to test if two expressions are equal to each other. If statement always use ==.

Putting a ; at the end of if (test);
Remember that the if statement ends after if (test) statement; or use curly brackets if (test) { statements; }.

Using two if statements one after the other, instead of an if–else statement.

Having trouble with overly-complex conditionals which are two or more boolean expressions joined by && or ||.

Not understanding that || is an inclusive-or where one or both of the operands must be true in order for the entire expression to be true.