How would I check a string for a certain letter in Python?
Question:
How would I tell Python to check the below for the letter x and then print “Yes”? The below is what I have so far…
dog = "xdasds"
if "x" is in dog:
print "Yes!"
Answers:
Use the in keyword without is.
if "x" in dog:
print "Yes!"
If you’d like to check for the non-existence of a character, use not in:
if "x" not in dog:
print "No!"
in keyword allows you to loop over a collection and check if there is a member in the collection that is equal to the element.
In this case string is nothing but a list of characters:
dog = "xdasds"
if "x" in dog:
print "Yes!"
You can check a substring too:
>>> 'x' in "xdasds"
True
>>> 'xd' in "xdasds"
True
>>>
>>>
>>> 'xa' in "xdasds"
False
Think collection:
>>> 'x' in ['x', 'd', 'a', 's', 'd', 's']
True
>>>
You can also test the set membership over user defined classes.
For user-defined classes which define the __contains__ method, x in y is true if and only if y.__contains__(x) is true.
If you want a version that raises an error:
"string to search".index("needle")
If you want a version that returns -1:
"string to search".find("needle")
This is more efficient than the ‘in’ syntax
How would I tell Python to check the below for the letter x and then print “Yes”? The below is what I have so far…
dog = "xdasds"
if "x" is in dog:
print "Yes!"
Use the in keyword without is.
if "x" in dog:
print "Yes!"
If you’d like to check for the non-existence of a character, use not in:
if "x" not in dog:
print "No!"
in keyword allows you to loop over a collection and check if there is a member in the collection that is equal to the element.
In this case string is nothing but a list of characters:
dog = "xdasds"
if "x" in dog:
print "Yes!"
You can check a substring too:
>>> 'x' in "xdasds"
True
>>> 'xd' in "xdasds"
True
>>>
>>>
>>> 'xa' in "xdasds"
False
Think collection:
>>> 'x' in ['x', 'd', 'a', 's', 'd', 's']
True
>>>
You can also test the set membership over user defined classes.
For user-defined classes which define the __contains__ method, x in y is true if and only if y.__contains__(x) is true.
If you want a version that raises an error:
"string to search".index("needle")
If you want a version that returns -1:
"string to search".find("needle")
This is more efficient than the ‘in’ syntax