Question

I am writing some code and need the user to input a file for use in the program:

file=input('input file name')

however, whenever you then input a file name (or anything for that matter) an error pops up saything that whatever has just been input is not defined and ends the program. What is causing this to happen?

Thanks

Answer 1

This is important:

input([prompt]) -> value
Equivalent to eval(raw_input(prompt)).

Input will try to eval your input

Check this

In [38]: l =  input("enter filename: ")
enter filename: dummy_file
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
C:\Python27\<ipython-input-37-b74d50e2a058> in <module>()
----> 1 l =  input("enter filename: ")

C:\Python27\<string> in <module>()

NameError: name 'dummy_file' is not defined


In [39]: input /?
Type:       builtin_function_or_method
Base Class: <type 'builtin_function_or_method'>
String Form:<built-in function input>
Namespace:  Python builtin
Docstring:
input([prompt]) -> value

Equivalent to eval(raw_input(prompt)).

In [40]: file = raw_input("filename: ")
filename: dummy_file

In [41]: file
Out[41]: 'dummy_file'

using raw_input has it’s disadvantages though.