The error occurs, as you have been told, because raw_inputit does not exist in Python 3.X. This has been and will continue to be a source of confusion because the functions input()do not do the same Python 2thing in Python 3despite having the same name.

In Python 2.xboth functions, we are going to clarify a little what each one does:

Python 2.x :

• raw_input()Returns a line of user input as is, raw and always returns a character string , an object str(ASCII) containing the input.

  >>> v = raw_input('Introduce algo: ')
  Introduce algo: 24
  >>> print v
  24
  

  But remember that the variable v does not contain a number, it is not a int, it is a string of characters (text). If we try to operate as an integer:

  >>> v + 6
  

  We get an error telling us that we cannot add a string with an integer:

  Traceback (most recent call last):
    File "<pyshell#2>", line 1, in <module>
      v + 6
  TypeError: cannot concatenate 'str' and 'int' objects
  

  To make it an integer, you have to convert it by doing an explicit casting (Python has strong typing, it never does an implicit casting to adapt the type of the variable to the context):

  >>> v = int(v)
  >>> v + 6
  30
  

• input()expects valid Python expressions to be passed to it . That is, only Python code can be passed to it, and the function evaluates and processes it as such.

  >>> v = input('Ingresa algo que pueda evaluar: ')
  Ingresa algo que pueda evaluar: 2 + 5 * 3
  >>> print v
  17
  

  What happened here? Well, it input()has taken the expression and since it is valid Python code, it has evaluated it and has performed the operations. We could think that it input()only accepts numbers but this is false, I don't know why it has become so widespread, to the point of generalizing the idea that it inputis for entering scalars and raw_inputfor strings. Accept any valid expression in Python:

  Concatenating two strings:

  >>> v = input('Ingresa algo que pueda evaluar: ')
  Ingresa algo que pueda evaluar: 'hola ' + 'mundo'
  >>> print(v)
  'hola mundo'
  

  Creating a list using list compression:

  >>> v = input('Ingresa algo que pueda evaluar: ')
  Ingresa algo que pueda evaluar: [n *2 for n in range (10)]
  >>> print(v)
  [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
  

  We can pass a string with no problem, but a string is passed to it using quotes, just as we declare a string literal in code:

  >>> v = input('Ingresa algo que pueda evaluar: ')
  Ingresa algo que pueda evaluar: "hola mundo"
  >>> print(v)
  hola mundo
  

  Another very common mistake is to try to use inputin Python 2 as it is used in Python 3, with the idea of ​​assigning the string entered by the user to a variable:

  >>> nombre = input('Ingrese su nombre: ')
  Ingrese su nombre: Jogofus
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  NameError: name 'Jogofus' is not defined
  

  We have an error:

  NameError: name 'Jogofus' is not defined

  exactly the same as if we try to use a variable that is not defined before we do:

  >>> Jogofus + 5
  

  If we have understood what it does inputin Python 2, it should not surprise us, when evaluating the string 'Jogofus' entered, it tries to look for the name Jogofusin the global namespace (as if it were the name of a variable, a function, a class, etc).

Python 3.x:

• input()does the same as raw_input()in Python 2.x. Reads a line of input from standard input and returns it raw in an object str(UTF-8). In fact, it's the same function but renamed, the only difference is that in Python 2 strit's ASCII while in Python 3 it's a Unicode (UTF-8) string.

• The former input()is roughly equivalent to eval(), which takes a string of text and tries to evaluate it as if it were valid Python code. The difference is that instead of reading the string from standard input as you do inputin Python 2, you must pass it as an argument:

  >>> v = eval(input('Ingresa algo que pueda evaluar: '))
  Ingresa algo que pueda evaluar: 'hola ' + 'mundo'
  >>> print(v)
  'hola mundo'
  

In short, if you use Python 3.xonly exists input()and always returns a string. If you use Python 2.x raw_inputdoes the same thing as input()in Python 3.x(accepts any string and always returns an object str) while input()only accepting expressions that are syntactically valid in Python (otherwise it will throw an error) and evaluating them afterwards.

I advise you that when you look at documentation or tutorials you look at which version they use because the changes from branch 2 to 3 were important. Here is a list of the most significant:

https://docs.python.org/3/whatsnew/3.0.html

Warning: The use of input(Python 2.x) or evalshould be very careful and never use them to capture unfiltered user input in sensitive applications (a web server for example). Remember that they accept Python code and evaluate it. A user may enter code that is harmful to the program or system, either unintentionally or maliciously. An example, if we have imported the module osin the namespace where input/ is executed eval, nothing prevents a user if the script has sufficient privileges to enter os.system('rm -rf /')and send all the files of the system to the afterlife. exec, evale input(Python 2) expose to malicious code injection, this does not mean that they are the devil and that they should not exist, they are very useful and powerful tools in many cases, but you have to be aware and consistent with their potential and danger .

The function raw_input()was renamed to input()in Python 3.x

The old input()one can be emulated witheval(input())

For python2 there are 2 functions input()and raw_input(), the first one is for numeric values, while the second one is for text strings; but this changes in python3 , the raw_input()has been renamed to input(), and the old one input()has been removed. So if you use python 3 you should use input()instead ofraw_input()