Section 7.5 Omitting the else Clause: Unary Selection
Another form of the
if statement is one in which the
else clause is omitted entirely. This creates what is sometimes called unary selection. In this case, when the condition evaluates to
True, the statements are executed. Otherwise the flow of execution continues to the statement after the body of the
What would be printed if the value of
x is negative? Try it.
Check your understanding
What does the following code print?
x = -10 if x < 0: print("The negative number ", x, " is not valid here.") print("This is always printed")
a. This is always printed b. The negative number -10 is not valid here This is always printed c. The negative number -10 is not valid here
It will cause an error because every if must have an else clause.
- Every else-block must have exactly one corresponding if-block. If you want to chain if-else statements together, you must use the else if construct, described in the chained conditionals section.
- This will cause an error because the second else-block is not attached to a corresponding if-block.
Will the following code cause an error?
x = -10 if x < 0: print("The negative number ", x, " is not valid here.") else: print(x, " is a positive number") else: print("This is always printed")