From dccfd530b5ea82f176ef190c2a3c37fa70a87a4d Mon Sep 17 00:00:00 2001
From: sgoudham <sgoudham@gmail.com>
Date: Wed, 14 Jul 2021 01:27:17 +0100
Subject: [PATCH] Implement Add, Subtract, Multiply and Divide Functionality

---
 calculator/calculator.c | 14 ++++-----
 calculator/utility.c    | 67 +++++++++++++++++++++++++++++++++++++++++
 calculator/utility.h    | 14 +++++++++
 3 files changed, 87 insertions(+), 8 deletions(-)
 create mode 100644 calculator/utility.c

diff --git a/calculator/calculator.c b/calculator/calculator.c
index 945a0e3..82e239b 100644
--- a/calculator/calculator.c
+++ b/calculator/calculator.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include "utility.h"
 
 int main() {
     char operator; 
@@ -13,26 +14,23 @@ int main() {
             break;
         }
 
-        printf("Enter First Operand: ");
-        scanf("%lf", &firstOperand);
-        printf("Enter Second Operand: ");
-        scanf("%lf", &secondOperand);
+        getOperands(&firstOperand, &secondOperand);
 
         switch (operator) {
             case '+':
-
+                add(firstOperand, secondOperand);
                 break;
 
             case '-':
-
+                subtract(firstOperand, secondOperand);
                 break;
 
             case '*':
-
+                multiply(firstOperand, secondOperand);
                 break;
 
             case '/':
-
+                divide(firstOperand, secondOperand);
                 break;
 
             default:
diff --git a/calculator/utility.c b/calculator/utility.c
new file mode 100644
index 0000000..c7e92ba
--- /dev/null
+++ b/calculator/utility.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include "utility.h"
+
+const char operators[] = {'+', '-', '*', '/'};
+
+char enumToString(MathOperator mathOperator) {
+    return operators[mathOperator];
+}
+
+void println(double firstOperand, MathOperator mathOperator, double secondOperand, double result) {
+    printf("%0.2lf %c %0.2lf = %0.2lf\n\n", firstOperand, enumToString(mathOperator), secondOperand, result);
+}
+
+double doOperation(double firstOperand, double secondOperand, MathOperator mathOperator) {
+    double result = 0.0;
+
+    switch (mathOperator) {
+        case ADD:
+            result = firstOperand + secondOperand;
+            break;
+        
+        case SUBTRACT:
+            result = firstOperand - secondOperand;
+            break;
+
+        case MULTIPLY:
+            result = firstOperand * secondOperand;
+            break;
+
+        case DIVIDE: 
+            result = firstOperand / secondOperand;
+            break;
+
+        default:
+            printf("Sorry don't recognise the given operator!\n");
+            break;
+        }
+    
+    return result;
+}
+
+void getOperands(double *firstOperand, double *secondOperand) {
+    printf("Enter First Operand: ");
+    scanf("%lf", firstOperand);
+    printf("Enter Second Operand: ");
+    scanf("%lf", secondOperand);
+}
+
+void add(double firstOperand, double secondOperand) {
+    double result = doOperation(firstOperand, secondOperand, ADD);
+    println(firstOperand, ADD, secondOperand, result);
+}
+
+void subtract(double firstOperand, double secondOperand) {
+    double result = doOperation(firstOperand, secondOperand, SUBTRACT);
+    println(firstOperand, SUBTRACT, secondOperand, result);
+}
+
+void multiply(double firstOperand, double secondOperand) {
+    double result = doOperation(firstOperand, secondOperand, MULTIPLY);
+    println(firstOperand, MULTIPLY, secondOperand, result);
+}
+
+void divide(double firstOperand, double secondOperand) {
+    double result = doOperation(firstOperand, secondOperand, DIVIDE);
+    println(firstOperand, DIVIDE, secondOperand, result);
+}
diff --git a/calculator/utility.h b/calculator/utility.h
index e69de29..e407d8e 100644
--- a/calculator/utility.h
+++ b/calculator/utility.h
@@ -0,0 +1,14 @@
+typedef enum {
+    ADD,
+    SUBTRACT,
+    MULTIPLY,
+    DIVIDE
+} MathOperator;
+
+extern const char operators[];
+
+void add(double firstOperand, double secondOperand);
+void subtract(double firstOperand, double secondOperand);
+void multiply(double firstOperand, double secondOperand);
+void divide(double firstOperand, double secondOperand);
+void getOperands(double *firstOperand, double *secondOperand);