What are if...else statement in Python?
Decision making is required when we want to execute a code only if a certain condition is satisfied.
The
if…elif…else
statement is used in Python for decision making.Python if Statement Syntax
if test expression: statement(s)
Here, the program evaluates the
test expression
and will execute statement(s) only if the text expression is True
.
If the text expression is
False
, the statement(s) is not executed.
In Python, the body of the
if
statement is indicated by the indentation. Body starts with an indentation and the first unindented line marks the end.
Python interprets non-zero values as
True
. None
and 0
are interpreted as False
.Python if Statement Flowchart

Python if...else Statement
Syntax of if...else
if test expression: Body of if else: Body of else
The
if..else
statement evaluates test expression
and will execute body of if
only when test condition is True
.
If the condition is
False
, body of else
is executed. Indentation is used to separate the blocks.Python if..else Flowchart

Python if...elif...else Statement
Syntax of if...elif...else
if test expression: Body of if elif test expression: Body of elif else: Body of else
The
elif
is short for else if. It allows us to check for multiple expressions.
If the condition for
if
is False
, it checks the condition of the next elif
block and so on.
If all the conditions are
False
, body of else is executed.
Only one block among the several
if...elif...else
blocks is executed according to the condition.
The
if
block can have only one else
block. But it can have multiple elif
blocks.Flowchart of if...elif...else

Python Nested if statements
We can have a
if...elif...else
statement inside another if...elif...else
statement. This is called nesting in computer programming.
Any number of these statements can be nested inside one another. Indentation is the only way to figure out the level of nesting. This can get confusing, so must be avoided if we can.
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