python input() not working as expected [duplicate]

Question

I am a python newbie.I am getting familiar with loops and tried this example from a book

while True:
        s = input('Enter something : ')
        if s == 'quit':
                break
        print('Length of the string is', len(s))
print('Done')

However the output is as follows

Enter something : ljsdf
Traceback (most recent call last):
  File "trial_2.py", line 2, in <module>
    s = input('Enter something : ')
  File "<string>", line 1, in <module>
NameError: name 'ljsdf' is not defined

Answer 1

You have to use raw_input() instead (Python 2.x), because input() is equivalent to eval(raw_input()), so it parses and evaluates your input as a valid Python expression.

while True:
        s = raw_input('Enter something : ')
        if s == 'quit':
                break
        print('Length of the string is', len(s))
print('Done')

Note:

input() doesn't catch user errors (e.g. if user inputs some invalid Python expression). raw_input() can do this, because it converts the input to a string. For futher information, read Python docs.