9.13 Calculate expression then check condition
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In comparison operations the left operand can now contain calculations
of an expression, including increment and decrement. For example:
IF (i=a+2 != 0 )...
IF ( i++ )...
IF ( a-- )...
IF ( i+=4 == 0 )...
In all these example, first the expression in the left part of the
comparison operation is calculated, and then the result is compared with
the right part of the expression to be compared.