From f490ef5ef0414722c4b27125e413a326525119b4 Mon Sep 17 00:00:00 2001
From: Lee <sara.lee.higgins@gmail.com>
Date: Wed, 5 Feb 2020 10:26:58 -0800
Subject: [PATCH] Add calculator.rb

---
 calculator.rb | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 calculator.rb

diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..54a366d
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,84 @@
+## METHODS ##
+
+# Modifies the Float class with method that converts the float to an integer if the integer is equal to the original float (Source: Yehuda Katz, https://stackoverflow.com/questions/1077346/ruby-round-float-to-int-if-whole-number)  
+class Float
+	def prettify
+		to_i == self ? to_i : self
+  end
+end
+
+# Define a method that executes an until loop to check whether the user input is an integer or a float (i.e., if no errors are returned when the input is a parameter of the Integer class); if true, returns the input as a float that invokes the prettify method; if false, prompts for a valid number
+def verify_num(input)
+	input = gets.chomp
+
+	until (Integer(input) rescue false) || (Float(input) rescue false)
+		puts "Please enter a valid number."
+		input = gets.chomp
+	end
+	
+	return input.to_f.prettify
+end
+
+# Define a method that executes an until loop to check whether the user input, converted to downcase, includes any of the valid operator options; if true, returns the input; if false, prompts for a valid option
+def verify_op(operation)
+	operation = gets.chomp
+	until ["1", "add", "+", "2", "subtract", "-", "3", "multiply", "*", "4", "divide", "/", "5", "exponent", "^", "6", "remainder", "%"].include?(operation.downcase)
+		puts "Please enter a valid option."
+		operation = gets.chomp
+	end
+
+	return operation
+end
+
+## PROGRAM START ##
+
+# Print an introductory message
+puts "Welcome to the Calculator Program!\n\n" 
+# Prompt the user to choose a math operator, accepting both the name and symbol for each possible choice
+puts "Which operator would you like to use?"
+puts "1. add(+)"
+puts "2. subtract(-)"
+puts "3. multiply(*)"
+puts "4. divide(/)"
+puts "5. exponent(^)"
+puts "6. remainder(%)\n\n"
+# Invoke the verify_op method and assign the output to the operation variable
+operation = verify_op(operation)
+
+# Prompt the user for two numbers, invoke the verify_num method and assign the output to the num_1 and num_2 variables, respectively
+puts "\nPlease enter the first number."
+num_1 = verify_num(num_1)
+puts "\nPlease enter the second number."
+num_2 = verify_num(num_2)
+	
+# Execute a while loop that checks whether the value assigned to operation includes any of the strings associated with the divide or modulo operators AND whether the value assigned to num_2 is 0; if true, prints an error message prompting the user to choose a number greater than 0, invokes the verify_num method, and assigns the new number to the num_2 variable
+while ["4", "divide", "/", "6", "remainder", "%"].include?(operation) && num_2 == 0
+		puts "Error! Please enter a number greater than zero."
+		num_2 = verify_num(num_2)
+end
+
+# Execute a case statement that checks the value assigned to operation; depending on which operator the user chose, the operator variable is assigned with a symbol that best represents the operator, and the result variable is assigned the output of num_1 + num_2, num_1 - num_2, etc.
+case operation
+	when "1", "add", "+"
+		operator = :+
+		result = num_1 + num_2
+	when "2", "subtract", "-"
+		operator = :-
+		result = num_1 - num_2
+	when "3", "multiply", "*"
+		operator = :*
+		result = num_1 * num_2
+	when "4", "divide", "/"
+		operator = :/
+		result = num_1 / num_2
+	when "5", "exponent", "^"
+		operator = :^
+		result = num_1 ** num_2
+	when "6", "remainder", "%"
+		operator = :%
+		result = num_1 % num_2
+end
+
+# Print a confirmation message, the equation, and the result
+puts "\nThank you! Here is your result:"
+puts "#{num_1} #{operator} #{num_2} = #{result}"
\ No newline at end of file