ruby - syntax error, unexpected tOP_ASGN - ruby

Question

The following is a portion of my code. Any advice is appreciated.
def how_many_guesses?
guesses = 0
end
def guess
puts "Please type a number between 1 and a 100."
gets.chomp
end
def correct?
if guess == guess
puts "You have already guessed this number, try again!"
guess
elsif guess == random_num
you_are_correct
elsif guess > correct_num
puts "Too high!"
how_many_guesses? += 1
guess
else
puts "Too low!"
how_many_guesses? += 1
guess
end
end
The error I received was:
syntax error, unexpected tOP_ASGN
how_many_guesses? += 1
I don't understand what unexpected tOP_ASGN means.

Answer 1

As other commented you are trying to assign a value to a function.
You can use some other approaches for example using a class variable, or a setter method.
In the first case you use an instance variable, and you just increment or decrement its value:
class Guess
def initialize
#guesses = 0
end
def guess
puts "Please type a number between 1 and a 100."
gets.chomp
end
def correct?
if guess == guess
puts "You have already guessed this number, try again!"
guess
elsif guess == random_num
you_are_correct
elsif guess > correct_num
puts "Too high!"
#guesses += 1
guess
else
puts "Too low!"
#guesses += 1
guess
end
end
end
In this example you can use attr_reader to publish the guesses variable
The other way, more c++ style, is using getter and setter functions:
class Guess
def initialize
#guesses = 0
end
def get_guesses
#guesses
end
def set_guesses(guesses)
#guesses = guesses
end
def how_many_guesses?
guesses = 0
end
def guess
puts "Please type a number between 1 and a 100."
gets.chomp
end
def correct?
if guess == guess
puts "You have already guessed this number, try again!"
guess
elsif guess == random_num
you_are_correct
elsif guess > correct_num
puts "Too high!"
set_guesses(get_guesses + 1)
guess
else
puts "Too low!"
set_guesses(get_guesses + 1)
guess
end
end
end
This is another solution, but it is not recommended in ruby.
EDIT: Some comments included the option of using global variables, just don't!

Answer 2

To elaborate on #Gavriel's answer, functions are singletons, while += is an assignment operator
Your code can be rewritten to basically look like so:
def how_many_guesses?
guesses = 0
end
how_many_guesses? = how_many_guesses? + 1
Which is impossible, as you can not assign to function symbols in this manner. It is possible to redefine a function on the fly due to Ruby's robust metaprogramming capabilities, but that falls far outside the scope of this question.
The easiest way for you to fix it is to do the following:
numGuesses = how_many_guesses?
numGuesses += 1

Answer 3

how_many_guesses? is a function, you can only assign a value to a variable. But maybe you should read a bit more about functions generally, as your code indicates you might need some clarification.
What you probably wanted to do is something like:
$guesses = 0
and
$guesses += 1
You don't need a function here I think.
But the bigger problem will be that every time you wrote down "guess" it will wait for you to type a number.
if guess == guess # here you'll enter 2 numbers
puts "You have already guessed this number, try again!"
guess # here you'll enter another one
elsif guess == random_num # and if the 1st and 2nd numbers were different then you'll be asked another one here...

Answer 4

Option 1:
Replace all how_many_guesses? with $guesses making it a global variable. Define guesses at the top of the file: $guesses = 0
Option 2 (Better):
Put everything in a class and make guesses an instance variable:
class GuessGame
def initialize
#guesses = 0
end
def guess
# ...
end
def correct?
# ...
#guesses += 1
end
end