I am figuring out how does Ruby return works, so I have a problem: I have a list and a function, that push different statements on it. And I need to figure out - how to recall function until user enter statement, that does not included on this list?
$my_list = []
def add_element()
user_input = gets.to_i
if $my_list.include?(user_input)
puts 'There is already such number in list, re-enter your number. please.'
return user_input
else
puts "Your number is - #{user_input}"
$my_list.push(user_input)
end
end
add_element
The Problem is that it can see if value already in list but I cannot figure out how to ask user to re-enter it again until he enter not duplicated number.
To expand on Mark's idea,
$my_list = []
def add_element()
user_input = gets.to_i
while my_list.include?(user_input)
puts 'There is already such number in list, re-enter your number. please.'
user_input = gets.to_i
end
$my_list.push(user_input)
end
add_element
Should do the trick
Related
I have to write a program which asks the user to enter a number.
The program keeps on asking the user for a number until the user types 'Stop'
at which point the sum of the numbers that the user has entered should be printed.
I've tried many,many things and none of my ideas work.
This is what I have - but I can that it isn't correct. What am I doing wrong?
I've only used while loops and arrays
total_user_input = []
# As long as the user inputs a number, the program will keep putting Give me a number
# and then adding that number to the total_user_input array.
puts "Give me a number: "
while user_input = gets.chomp.to_i
#add the input to the array total_user_input
total_user_input.push(user_input.to_i)
puts "Give me a number: "
# If the user however types stop, then the loop is broken and we jump down to the
# sum bit - where all of the numbers in the total_user_input array are added together
# and printed. End of program!
if user_input == "stop"
break
end
sum = 0
total_user_input.each { |num|
sum += num
}
puts sum
end
The output isn't as it should be.
As others have identified the problems with your code let me suggest how you might reorganize it. Ruby provides many ways to execute loops but you many find it desirable to primarily relay on the method Kernel#loop and the keyword break. (As you will learn in time, loop is particularly convenient when used with enumerators.)
def sum_numbers
tot = 0
loop do
print 'Gimme a number: '
s = gets.chomp
break if s == 'Stop'
tot += s.to_i
end
tot
end
The keyword break can optionally take an argument (though why that is not mentioned in the doc I cannot say), in which case it (if a literal) or its value (if a variable or method) is returned by loop. Here one would generally see
break tot if s == 'Stop'
without the final line, tot. As the loop returns tot and that is the last calculation performed by the method, the method will return the final value of tot.
You could have instead written
return tot if user_input == 'Stop'
but I think most coders believe best practice dictates that one should not return from a method from within a loop (or from within nested loops) unless there is a good reason for doing so.
Some small points:
I used print rather than puts to that the user's entry will be shown on the same line as the prompt.
I used s (for "string") rather than user_input because it reduces the chance of spelling mistakes (e.g., user_imput), speeds reading, and (possibly a foible of mine), looks neater. True, s is not descriptive, but one only has to remember its meaning for three consecutive lines of code. Others may disagree.
You could write, break if s.downcase == 'stop' if you want, say, 'stop' or 'STOP' to have the same effect as 'Stop'.
'23O3'.to_i #=> 23 (that's an an oh, not a zero), so in real life you'd want to confirm that either 'Stop' or the string representation of a number had been typed.
This is how I would do this preferring to use loop do end syntax with a break when it should. Also added a bit more text so user knows what's happening.
total_user_input = []
puts 'Give me a number or "stop" to end: '
loop do
user_input = gets.chomp
total_user_input << user_input.to_i
puts "Give me a number: "
break if user_input.downcase == "stop"
end
puts "Total entered: #{total_user_input.inject(&:+)}" unless total_user_input.empty?
puts 'goodbye!'
Note these few things:
get.chomp.to_i will convert every input to integer. ("stop" or any non integer string will be 0)
Arrangement of the flow is quite messy.
total_user_input = []
puts "Give me a number: "
while user_input = gets.chomp.strip
total_user_input.push(user_input.to_i)
sum = 0
total_user_input.each { |num|
sum += num
}
puts sum
if user_input == "stop"
break
end
end
Hope you understand this.
Noob rubyist here, working through "Learn to Program." I've set up the below code to take user entries and sort, but I can't figure out how to end the program on a nil entry instead of the 'done' that is currently set. Setting the user == '', obviously terminates before it takes any input. Any help is greatly appreciated!
array = []
user = ''
puts "Type as many words as you like. Press enter to end."
until user == 'done'
user = gets.chomp
array.push user
end
puts
puts array.sort
Start your variable from nil, so that it executes the body at least the first time
user = nil
until user == ''
user = gets.chomp
array.push user
end
Here is another implementation that will not add the blank user to the array. Although it would be nice to use a construct more specific than loop, loop gives us exactly what we need.
users = []
loop do
user = gets.chomp
if user != ''
users << user
else
break
end
end
puts users
Your message says "Press enter to end". So I suggest you get the user input in one go, split the string into words, sort and display.
user = ''
puts "Type as many words as you like. Press enter to end."
user = gets.chomp
array = user.split
puts array.sort
So I've been messing around with Ruby for the first time after finishing the codecademy course up to "Object Oriented Programming, Part I" and I decided to start making a calculator. For some reason though, I get this error:
calc.rb:13:in `addition': undefined local variable or method `user_input' for main:Object (NameError)
from calc.rb:21:in `<main>'
I'm confused why it doesn't see my "user_input" array. Is it out of the scope of the method? Did I initialize it wrong?
Here's the code so you can see for yourself, it's obviously nothing sophisticated and it's not finished. I'm just trying to test for addition right now.
#!/usr/bin/env ruby
user_input = Array.new
puts "Would you like to [a]dd, [s]ubtract, [m]ultiply, or [d]ivide? "
type_of_math = gets.chomp
def addition
operator = :+
puts "Please enter the numbers you want to add (enter \"=\" to stop adding numbers): "
until gets.chomp == "="
user_input << gets.chomp.to_i
end
sum = user_input.inject(operator)
return sum
end
case type_of_math
when "a"
addition
when "s"
puts "Test for subtraction"
when "m"
puts "Test for multiplication"
when "d"
puts "Test for division"
else
puts "Wrong"
end
Consider this untested variation on your code. It's more idiomatic:
def addition
user_input = []
puts 'Please enter the numbers you want to add (enter "=" to stop adding numbers): '
loop do
input = gets.chomp
break if input == '='
user_input << input
end
user_input.map(&:to_i).inject(:+)
end
Notice that it puts user_input into the method. It also uses the normal [] direct assignment of an empty array to initialize it. Rather than chomp.to_i each value as it's entered it waits to do that until after the loop exits.
Instead of while loops, consider using loop do. They tend to be more easily seen when scanning code.
Also notice there's no return at the end of the method. Ruby automatically returns the last value seen.
I'm having trouble summing an array. Here's my existing code:
pageArray = Array.new
puts "How many pages long is the book you're reading?"
pageArray << gets.chomp
puts "Are you reading any other books right now?"
yn = gets.chomp
while yn != "no" do
puts "How many pages long is your next book?"
pageArray << gets.chomp
puts "Are you reading any other books right now?"
yn = gets.chomp
end
pageSum = pageArray.reduce(:+)
puts pageSum
When I go through and enter the values 100 and 50, the final return is "10050," rather than "150." Am I missing something obvious?
The code could be written more clearly, and more Ruby-like. Here's some untested code that is more idiomatic:
page_array = []
puts "How many pages long is the book you're reading?"
page_array << gets.chomp
loop do
puts 'Are you reading any other books right now?'
yn = gets.chomp.downcase
break if yn == 'no'
puts 'How many pages long is your next book?'
page_array << gets.chomp.to_i
end
page_sum = page_array.reduce(:+)
puts page_sum
Notice:
variables in Ruby are in snake_case, notInCamelCase.
loop do will loop forever. Simply break when you've received the break value.
you should fold the case of the value used as a break to catch variations in 'y' and 'Y'.
take the time to format your code so it's easily read, even for quick tests. It's amazing how often code we think is just a test actually gets put into production, so do it right the first time.
You are entering strings and concatenating them.
Use gets.chomp.to_i
You need to change the string you get from gets to an int.
pageArray << gets.chomp.to_i
I am trying to solve the "24" game. The point of the game is to generate 4 random integers from 1-9 and ask the player to use addition, subtraction, multiplication, or division to get the number 24. My code runs fine until a player enters a number, and then I get "Command not found". Can someone please take a look at this:
def evaluate (input,solved_v)
input = eval (input.to_f)
#convert to a float and then evaluates it; it computes
if input == 24
solved_v = true
puts "great job! you did it!"
else
puts "please try again"
end
end
def test_entry (input)
if input.scan(%r{[^\d\s()+*/-]}).empty?
#this scan detects letters and special characters because only numbers work
true
else
false
end
end
puts
puts "try to use +, -, / or * to"
puts "get 24 from the integers provided"
puts
series = (1..4).collect{ rand(1..9)}
#generates 4 random numbers between 1 and 9
for i in series
puts i
end
puts "Please guess"
solved = false
unless solved = true
user_input = gets.chomp
if test_entry(user_input) == true
evaluate(user_input)
else
puts "invalid characters entered"
puts "please try again"
puts
end
end
There are numerous problems with your program.
Don't put spaces between your method names and parentheses.
eval takes a string argument, not a float.
Ruby passes arguments by value, so solved_v isn't going to get
returned. Make it the return value of your evaluate method. I'd also
suggest renaming your methods to express their boolean intent. See below...
Don't check boolean expressions for equality to true or false, just use them.
def correct?(input)
if eval(input) == 24
puts "great job! you did it!"
true
else
puts "please try again"
false
end
end
def good_entry?(input)
input.scan(%r{[^\d\s()+*/-]}).empty?
end
and they get used as follows
while true
user_input = gets.chomp
if good_entry?(user_input)
break if correct?(user_input)
else
...
end
end
Finally, note that you're not actually checking that the input provided by the user uses only the supplied random numbers.