Python - pass Statement

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Python pass Statement

Python pass statement is used when a statement is required syntactically but you do not want any command or code to execute. It is a null which means nothing happens when it executes. This is also useful in places where piece of code will be added later, but a placeholder is required to ensure the program runs without errors.

For instance, in a function or class definition where the implementation is yet to be written, pass statement can be used to avoid the SyntaxError. Additionally, it can also serve as a placeholder in control flow statements like for and while loops.

Syntax of pass Statement

Following is the syntax of Python pass statement −

pass

Example of pass Statement

The following code shows how you can use the pass statement in Python −

for letter in 'Python':
   if letter == 'h':
      pass
      print ('This is pass block')
   print ('Current Letter :', letter)
print ("Good bye!")

When the above code is executed, it produces the following output −

Current Letter : P
Current Letter : y
Current Letter : t
This is pass block
Current Letter : h
Current Letter : o
Current Letter : n
Good bye!

Dumpy Infinite Loop with pass Statement

This is simple enough to create an infinite loop using pass statement in Python.

Example

If you want to code an infinite loop that does nothing each time through, do it as shown below −

while True: pass  
# Type Ctrl-C to stop                

Because the body of the loop is just an empty statement, Python gets stuck in this loop.

Using Ellipses (...) as pass Statement Alternative

Python 3.X allows ellipses (coded as three consecutive dots ...) to be used in place of pass statement. Both serve as placeholders for code that are going to be written later.

Example

For example if we create a function which does not do anything especially for code to be filled in later, then we can make use of ...

def func1():
   # Alternative to pass
   ...                   

# Works on same line too
def func2(): ...          
 # Does nothing if called
func1()                  
func2()