Alena's Calculator

Calculator.rb

@@ -0,0 +1,77 @@
+# checks whether user wrote correct operation
+def math()
+  operations = ["add", "+", "subtract", "-", "multiply", "*", "divide", "/", "raise", "^", "modulo", "%"]
+  symbol = gets.chomp
+  until operations.include?(symbol)
+    print "That's not a valid entry, please try again: "
+    symbol = gets.chomp
+  end
+  return symbol
+end
+
+# beginning of the code
+print "What kind of math would you like to perform? "
+command = math()
+
+# checks whether user wrote a number
+def read_number(prompt)
+  error_msg_1 = "Uh oh, invalid value. Please try again."
+  number = nil
+  while number == nil
+    print prompt
+    user_input = gets.chomp
+    if user_input.include?(".")
+      # Integer() will convert input to a number or it will throw an error
+      # that will be caught by the rescue clause if input is not a number
+      # rescue prints error message and continues execution of the code
+      number = Float(user_input) rescue puts(error_msg_1)
+    else
+      number = Integer(user_input) rescue puts(error_msg_1)
+    end
+  end
+  return number
+end
+
+first_number = read_number("What is the first number? ")
+
+second_number = read_number("What is the second number? ")
+
+# performs calculation based on user's input
+case command
+when "add", "+"
+  result = first_number + second_number
+  command = "+"
+when "substract", "-"
+  result = first_number - second_number
+  command = "-"
+when "multiply", "*"
+  result = first_number * second_number
+  command = "*"
+when "divide", "/"
+  # catches the division by 0 that throws an error
+  # begin contains code that potentially may throw an error
+  begin
+    result = first_number / second_number
+    # rescue catches and handles error
+    # prints a message
+  rescue
+    puts("Oh no. We cannot divide by 0.")
+    # terminates the program
+    exit
+  end
+when "raise", "^"
+  result = first_number ** second_number
+  command = "^"
+when "modulo", "%"
+  command = "%"
+  begin
+    result = first_number % second_number
+  rescue
+    puts("Oh no. We cannot divide by 0.")
+    exit
+  end
+  command = "%"
+end
+
+# prints the result based on the user input
+puts "#{first_number} #{command} #{second_number} = #{result}"