Adding Calc Features (+,-,*,**,/)

calc.dart

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+import 'dart:convert';
+import 'dart:io';
+import 'dart:math';
+
+class Calc {
+  // instance fiels
+  double num1;
+  double num2;
+
+  // constructor
+  Calc(double firstNum, double secondNum) {
+    this.num1 = firstNum;
+    this.num2 = secondNum;
+  }
+
+  //class method
+  //class methods
+  double add(double firstNum, double secondNum) {
+    return firstNum + secondNum;
+  }
+
+  double subtract(double firstNum, double secondNum) {
+    return firstNum - secondNum;
+  }
+
+  double multiply(double firstNum, double secondNum) {
+    return firstNum * secondNum;
+  }
+
+  double expontentiate(double firstNum, double secondNum) {
+    // Math.pow returns a double, so use typecasting to account for large numbers
+
+    double exponentProd = pow(firstNum, secondNum);
+
+    return exponentProd;
+  }
+
+  double divide(double firstNum, double secondNum) {
+    return firstNum / secondNum;
+  }
+
+  static void backToMainMenu() {
+    print("\nReturning to main menu...\n");
+    wholeThing();
+  }
+
+  static void wholeThing() {
+    // TODO : adding a Delay
+
+    print("""
+        \nWelcome to the Dart Calculator!
+        \n=============================== 
+        \nThis calculator performs operations on two numbers. 
+        \nPlease type your first number \nType 'exit' to exit at anytime! \n""");
+
+    String firstInput =
+        stdin.readLineSync(encoding: Encoding.getByName('utf-8'));
+    firstInput = firstInput.trim();
+    double firstNum = 0.0;
+
+    if (firstInput == "exit") {
+      exit(0);
+    } else {
+      firstNum = double.parse(firstInput);
+    }
+
+    print("\nGreat! Now input your second number.\n");
+
+    String secondInput =
+        stdin.readLineSync(encoding: Encoding.getByName('utf-8'));
+    secondInput = secondInput.trim();
+    double secondNum = 0.0;
+
+    if (secondInput == "exit") {
+      exit(0);
+    } else {
+      secondNum = double.parse(secondInput);
+    }
+
+    Calc calc1 = new Calc(firstNum, secondNum);
+
+    print("""\nAwesome! Now, choose the operation you want.
+    \nType + for addition
+    \nType - for subtraction
+    \nType * for multiplication
+    \nType ** to raise the first number to the power of the second
+    \nType / to divide""");
+
+    String operator = stdin.readLineSync(encoding: Encoding.getByName("utf-8"));
+    operator = operator.trim();
+
+    switch (operator) {
+      case "+":
+        print("${calc1.num1} plus ${calc1.num2} equals = ${calc1.add(firstNum, secondNum)}");
+        backToMainMenu();
+        break;
+      case "-":
+        print("${calc1.num1} minus ${calc1.num2} equals = ${calc1.subtract(firstNum, secondNum)}");
+        backToMainMenu();
+        break;
+      case "*":
+        print("${calc1.num1} multiplied by ${calc1.num2} equals = ${calc1.multiply(firstNum, secondNum)}");
+        backToMainMenu();
+        break;
+      case "**":
+        print("${calc1.num1} raised to the power of ${calc1.num2} equals = ${calc1.expontentiate(firstNum, secondNum)}");
+        backToMainMenu();
+        break;
+      case "/":
+        print("${calc1.num1} divided by ${calc1.num2} equals = ${calc1.divide(firstNum, secondNum)}");
+        backToMainMenu();
+        break;
+      case "exit":
+        exit(0);
+        break;
+      default:
+        print("Input not recognized.");
+        backToMainMenu();
+        break;
+    }
+  }
+}

main.dart

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+import 'calc.dart';
+
+void main(List<String> args) {
+  Calc.wholeThing();
+}