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This chapter is from the book

2.11 if Statement

The standard if conditional statement follows this syntax:

if expression:
   if_suite

If the expression is non-zero or True, then the statement if_suite is executed; otherwise, execution continues on the first statement after. Suite is the term used in Python to refer to a sub-block of code and can consist of single or multiple statements. You will notice that parentheses are not required in if statements as they are in other languages.

if x < .0:
    print '"x" must be atleast 0!'

Python supports an else statement that is used with if in the following manner:

if expression:
    if_suite
else:
    else_suite

Python has an “else-if” spelled as elif with the following syntax:

if   expression1:
     if_suite
elif expression2:
     elif_suite
else:
     else_suite

At the time of this writing, there has been some discussion pertaining to a switch or case statement, but nothing concrete. It is possible that we will see such an animal in a future version of the language. This may also seem strange and/or distracting at first, but a set of if-elif-else statements are not as “ugly” because of Python’s clean syntax. If you really want to circumvent a set of chained if-elif-else statements, another elegant workaround is using a for loop (see Section 2.13) to iterate through your list of possible “cases.”

You can learn more about if, elif, and else statements in the conditional section of Chapter 8.

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