Python Interpreter: Can't assign to literal [closed]

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I wrote a program with this code in it:

('<') = raw_input(v1), ('>') = raw_input(v2)开发者_运维百科

and recieve the message syntax error: can't assign to literal. What am I doing wrong?

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What am I doing wrong?

You're attempting to assign something the user enters to an instance of a String. That doesn't work.

To grab your question in a comment on another answer and attempt to incorporate it, if you want to be able to type v1 and have it return '<', you need to do this:

v1 = '<'

It sounds like, before you go much further, you strongly need to work through some of the basic programming concepts like assignment, variables, and functions.

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To take a stab at what you mean:

user_provided_value = raw_input("Say something:")

if user_provided_value == "v1":
    print "Heavier than a duck!"
elif user_provided_value == "v2":
    print "Lighter than a duck!"
else:
    print "You must enter either v1 or v2"

What you are saying is (ignoring the v1 and v2 variables):

('<')              #1 Set '<'
                   #2 [ ('<') is the same as simply saying '<' ]
 =                 #3 to be the result of assigning
                   #5 to a tuple composed of
 raw_input()       #6 what the user types in at the prompt
 ,                 #7 (the comma operator creates a tuple)
 ('>')             #8 And '>'
 =                 # to be 
 raw_input()       #4 what the user types in at the prompt

Typing those lines out in legible English, you are saying:

"Set '<' to be the result of assigning a user-defined value from raw_input() to the tuple raw_input(), '>'".

Saying, "Set some fixed value to be equal to the user-provided value" is the algebraic equivalent of saying "Set 5 to be equal to the value of the previous equation."

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* Since the comma operator is one of the least binding operators, you are actually setting the tuple composed of the strings raw_input(), '>' to be equal to the string from the second raw_input call.

The statement can be broken down as follows:

Set the string '<' to be the value resulting from evaluating the statement raw_input(), '>' = raw_input()

raw_input(), '>' = raw_input() is interpreted as:

Set the tuple composed of the results of calling raw_input() and '>' to be equal to the results of calling raw_input()

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Are you trying to get input with < and > as the prompts? If so, this is what you should be doing:

v1 = raw_input('<')
v2 = raw_input('>')

raw_input takes in the prompt as a parameter, and the output of this function call (what you type in the terminal) gets assigned into v1 and v2.

Another option in one line, since it looks like you are trying to do one line:

v1, v2 = raw_input('<'), raw_input('>')

The reason you are getting that error message is ('<') is what is called a literal. A literal is a value that is explicitly typed out in your code. Basically, not a variable. This is like saying 3 = len(mylist)... How do you assign the output of the len function to 3? You can't, because 3 is not a variable. You should only be assigning into a variable, in python (and most other languages) typically some sort of word-like set of characters, like v1 or myinput:

v1 = len(mylist)