Sean Valdivia - 3 months ago 8
Python Question

# Avoid Nesting If Statements? (Python 2.7)

I got the idea for this guessing game from a book, Invent With Python. I didn't like that the original script didn't cover the possibilities of re-guessing a number or incorrectly using a number not in 1 - 20, so I modified it. The program works great, however, I'm just wrapping my head around if/elif/else code blocks.

I'd like to rewrite the script without having to nest and if inside of an if. I can't even begin to wrap my head around how to do that. Can anyone please help me--just one example of how this program could work without nesting would be great!

Here's the little script in its entirety:

``````from random import randint
from sys import exit
name = raw_input("Hello! What's your name? ")
print "Well %s, I'm thinking of a number between 1 and 20." % name
print "Since I'm a benevolent computer program, I'll give you 6 guesses."
secret_number = randint(1, 20)

guesses_left = 6

while guessed_left > 0:
try:
guess = int(raw_input("Take a guess: "))

if guess >= 1 and guess <= 20 and guess not in already_guessed:
guesses_left -= 1

if guess == secret_number:
print "You win! %d was my secret number!" % secret_number
exit(0)
elif guess < secret_number:
print "Your guess is too low!"
elif guess > secret_number:
print "Your guess is too high!"

else:
print "Not a number between 1 - 20!"

print "You have %d guesses left!" % guesses_left

except ValueError:
print "Invalid input! Please try again!"
``````

Try it like this, using `continue` to exit the current iteration of the loop and start again at the top of the loop.

You also had a logic bug here:

``````if guess <= 1 and guess >= 20 and guess not in already_guessed:
``````

A number cannot possibly be both less than or equal to 1, and greater than or equal to 20. Your `and` should have been an `or` like this:

``````if (guess <= 1 or guess >= 20) and guess not in already_guessed:
``````

Or simpler:

``````if 1 <= guess <= 20 and guess not in already_guessed:
``````

Also, keep your `try/except` only around the things that can actually raise an exception (or shouldn't happen if an exception occurs:

``````from random import randint
import sys

name = raw_input("Hello! What's your name? ")
print "Well {}, I'm thinking of a number between 1 and 20.".format(name)
print "Since I'm a benevolent computer program, I'll give you 6 guesses."

secret_number = randint(1, 20)
guesses_left = 6

while guesses_left > 0:
print "You have {} guesses left!".format(guesses_left)

try:
guess = int(raw_input("Take a guess: "))
except ValueError:
print "Invalid input! Please try again!\n"
continue

# If the number is not between 1 and 20...
if not (1 <= guess <= 20):
print "Not a number between 1 - 20!"
continue

continue

guesses_left -= 1

if guess == secret_number:
print "You win! {} was my secret number!".format(secret_number)
sys.exit(0)
elif guess < secret_number:
print "Your guess is too low!\n"
elif guess > secret_number:
print "Your guess is too high!\n"
``````

Here's an example run:

``````Hello! What's your name? :)
Well :), I'm thinking of a number between 1 and 20.
Since I'm a benevolent computer program, I'll give you 6 guesses.
You have 6 guesses left!
Take a guess: 2

You have 5 guesses left!
Take a guess: 2

You have 5 guesses left!
Take a guess: 3

You have 4 guesses left!
Take a guess: 7