python input() not working as expected [duplicate]

Answer 1

you want raw_input() in python2

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

input() tries to evaluate (dangerously!) what you give it

Answer 2

In Python 2.x input() is designed to return numbers, int or float depending on the input from the user, you can also enter variable names.

you need to use:

raw_input('Enter something: ')

The error is caused because Python thinks that "ljsdf" is the name of a variable, and that's why it raises this exception:

NameError: name 'ljsdf' is not defined

becuase "ljsdf" is not defined as a variable. :D

raw_input() is safer to use, and then convert the input to whatever other type after :D

Answer 3

Your code will work fine in python 3.x

But if you are using python 2 you will have to input string using raw_input()

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

Answer 4

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.

Answer 5

It seems like you're using Python 2.x, while the code is expected to be run in Python 3.x.

input in Python 2.x evaluates the input string unlike input in Python 3.x.