Section 2.11. if Statement


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.



Core Python Programming
Core Python Programming (2nd Edition)
ISBN: 0132269937
EAN: 2147483647
Year: 2004
Pages: 334
Authors: Wesley J Chun

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