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How do I convert a string of letters to an integer?

Specifically, I take a word that the user enters, which is equivalent to a number (which the user didn't know).

my code:

animal = raw_input( > )  #and a user inputs cat
dog = 30 
cat = 10
frog = 5
print 10 + int(animal) #with the hope that will output 20

Not sure how to do this.

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6 answers


I would use a dictionary here

First, initialize the dictionary with the appropriate values.

Second, ask to enter user data.

Finally, get the value from the map using user input as the key.



animals_map = {"dog" : 30, "cat" : 10, "frog" : 5}

animal = raw_input('>') #and a user inputs cat
animal_number = animals_map[animal]

print 10 + int(animal_number) #with the hope that will output 20

EDIT:

As Ev. Kounis mentioned in a comment that you can use the get function so that you can get the default when the user input is not in the dictionary.

animals_map.get(animal, 0) # default for zero whether the user input is not a key at the dictionary.
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Make sure to process each input value:



types = {'dog': 30, 'cat': 10, 'frog': 5}

def getInput():
  try:
    return 10 + types[raw_input("Give me an animal: ")]
  except:
    print("BAD! Available animals are: {}".format(", ".join(types.keys())))
    return getInput()

print(getInput())
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animal = raw_input(>)
animal_dict = {'dog': 30, 'cat': 10, 'frog': 5}
number = animal_dict.get(animal, 0):
print 10+number
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Dictionary is the best idea, others have published. Just remember to handle bad input

animals = dict(dog=30,cat=10,frog=5)
animal = raw_input(">") # and a user inputs cat
if animal in animals:
    print "animal %s id: %d" % (animal,animals[animal])
else:
    print "animal '%s' not found" % (animal,)

https://docs.python.org/2/tutorial/datastructures.html#dictionaries

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You can use dictionaries for this:

animal = raw_input( > ) #and a user inputs cat

d = {'dog' : 30, 'cat' : 10, 'frog' : 5}

print 10 + d[animal]
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use eval

print (10 + eval(animal))

In your case, this will probably be a problem, but there may be a security issue when asking more complex questions. Refer to: Is eval in Python a bad practice?

Although in some cases, if it might be convenient to generate code as pointed out in the comment, use with caution.

EDIT: you can use a safer version that will evaluate the litteral :

import ast
print ( 10 + int(ast.literal_eval(  animal)))
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