From c4e36e19cbb23065d49187f092e54e6a54fa6463 Mon Sep 17 00:00:00 2001
From: Sigrid Benezra <35092766+sdbenezra@users.noreply.github.com>
Date: Wed, 8 Aug 2018 10:11:29 -0700
Subject: [PATCH] Create calculator.rb

---
 calculator.rb | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 calculator.rb

diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..2d605b1
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,76 @@
+# Calculator command line interface (CLI) that allows a user to perform simple arithmetic.
+
+# Array of valid operators
+operators = {"add" => "+", "subtract" => "-", "multiply" => "*", "divide" => "/"}
+
+def list_operators(op_array)
+  list_num = 0
+  op_array.each do |key, value|
+    puts "#{list_num += 1}.  #{key} (#{value}) "
+  end
+end
+
+# List available operators
+puts
+puts "Welcome to the Calculator program! Which operator would you like to use?"
+puts
+list_operators(operators)
+
+# Get input from operator
+puts
+puts "Please choose one operator (name or symbol):"
+operator = gets.chomp
+
+# Verify input as valid operator
+until operators.has_key?(operator) || operators.has_value?(operator)
+  puts "Sorry, that's not a valid operator"
+  puts "Please choose one operator (name or symbol) from the following"
+  list_operators(operators)
+  operator = gets.chomp
+end
+
+# method to check for valid number entry
+def check_num_entry(num)
+  regex = /\A[+-]?\d+(\.[\d+])?\z/
+  until regex.match(num)
+    puts "Please enter a valid positive or negative number. Thank you!"
+    num = gets.chomp
+  end
+end
+
+# Ask for numbers
+puts
+puts "Please enter a number"
+num_1 = gets.chomp
+check_num_entry(num_1)
+
+puts
+puts "Please enter another number"
+num_2 = gets.chomp
+check_num_entry(num_2)
+
+# Calculate result
+case operator
+  when "add", "+"
+    result = num_1.to_f + num_2.to_f
+  when "subtract", "-"
+    result = num_1.to_f - num_2.to_f
+  when "multiply", "*"
+    result = num_1.to_f * num_2.to_f
+  when "divide", "/"
+    if num_2 == "0" || num_2 == "0.0"
+      puts "Cannot divide by 0, please choose another number"
+      num_2 = gets.chomp
+      check_num_entry(num_2)
+    end
+    result = num_1.to_f / num_2.to_f
+end
+
+# Print result
+puts
+puts "The answer to #{num_1} #{operator} #{num_2} = #{result}"
+puts
+
+# Finish
+puts "Thank you for using the Calculator Progam"
+puts