if/else start the function again [closed] - ruby

Question

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Closed 10 years ago.
At the else, where the user didn't input a 1 or 2, the script should start over again after displaying the error message. How can I do that?
puts "Do you want to calculate celcius to fahrenheit (1) or fahrenheit to celcius(2)"
input = gets
if input == 1
puts "Please enter degrees in Celcius."
celcius = gets
fahrenheit = (celcius.to_i * 9 / 5) + 32
print "The result is "
print fahrenheit
puts "."
elseif input == 2
puts "Please enter degrees in Fahrenheit."
fahrenheit = gets
celcius = (fahrenheit.to_i / 9 * 5) - 32
print "The result is:"
print celcius
puts "."
else
puts "Please enter option 1 or 2"
end

Answer 1

You need to wrap the entire thing in a while loop and initialize the variable input to a value like nil.
The while loop's condition should check if the value is 1 or 2, and it will probably need to be converted to an integer with .to_i since gets will return a string.
# initialize to nil
input = nil
# Check if the current value (integer) is 1 or 2
while !([1,2].include?(input))
puts "Do you want to calculate celcius to fahrenheit (1) or fahrenheit to celcius(2)"
# Convert the string to an int after getting it as input
input = gets.to_i
if input == 1
puts "Please enter degrees in Celcius."
celcius = gets
fahrenheit = (celcius.to_i * 9 / 5) + 32
print "The result is "
print fahrenheit
puts "."
# elsif here, not elseif!!
elsif input == 2
puts "Please enter degrees in Fahrenheit."
fahrenheit = gets
celcius = (fahrenheit.to_i / 9 * 5) - 32
print "The result is:"
print celcius
puts "."
else
puts "Please enter option 1 or 2"
end
end
In fact, rather than a while loop, using an until loop (which Ruby has unlike many other languages) is more readable when testing for a negative condition:
until [1,2].include?(input)
...
end
The [1,2].include?(input) is a slicker way of writing
if input == 1 || input == 2
... that is easily expanded for additional values in the array.

Answer 2

This is it using a function.
puts "Do you want to calculate celcius to fahrenheit (1) or fahrenheit to celcius(2)"
def convert
input = gets
if input == 1
puts "Please enter degrees in Celcius."
celcius = gets
fahrenheit = (celcius.to_i * 9 / 5) + 32
print "The result is "
print fahrenheit
puts "."
elseif input == 2
puts "Please enter degrees in Fahrenheit."
fahrenheit = gets
celcius = (fahrenheit.to_i / 9 * 5) - 32
print "The result is:"
print celcius
puts "."
else
puts "Please enter option 1 or 2"
convert()
end
end
If input != (2 || 1) could work too.