# Common Mistakes¶

• Using two if‘s one after the other instead of an if and else.
• Trouble with complex conditionals which are two or more Boolean expressions joined by && or ||.
• Trouble with understanding or applying negation (!). See the section on DeMorgan’s Laws.
• Not understanding short circuit evaluation which is that if evaluation of the first Boolean expression is enough to determine the truth of a complex conditional the second expression will not be evaluated.
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