Simplified, added description and modified the code for better understanding.

Codes/Group A/Assignment-A3/A3.c

@@ -2,25 +2,29 @@
 #include <stdio.h>
 #include "A3.h"
 
-JNIEXPORT jint JNICALL Java_A3_add(JNIEnv *env, jobject obj, jint a, jint b) {
+// NOTE: No need to memorize this file
+// The contents of this file can be referenced from A3.h which is the generated header file
+// Refer explanation for more info: https://git.kska.io/sppu-te-comp-content/SystemsProgrammingAndOperatingSystem/src/branch/main/Codes/Group%20A/Assignment-A3/EXPLANATION.md
+
+JNIEXPORT jint JNICALL Java_A3_add(JNIEnv *env, jobject obj, jint a, jint b) { // Function for addition
     jint result = a + b;
     printf("\n%d + %d = %d\n", a, b, result);
     return result; // Return the result
 }
 
-JNIEXPORT jint JNICALL Java_A3_sub(JNIEnv *env, jobject obj, jint a, jint b) {
+JNIEXPORT jint JNICALL Java_A3_sub(JNIEnv *env, jobject obj, jint a, jint b) { // Function for subtraction
     jint result = a - b;
     printf("\n%d - %d = %d\n", a, b, result);
     return result; // Return the result
 }
 
-JNIEXPORT jint JNICALL Java_A3_mult(JNIEnv *env, jobject obj, jint a, jint b) {
+JNIEXPORT jint JNICALL Java_A3_mul(JNIEnv *env, jobject obj, jint a, jint b) { // Function for multiplication
     jint result = a * b;
     printf("\n%d * %d = %d\n", a, b, result);
     return result; // Return the result
 }
 
-JNIEXPORT jint JNICALL Java_A3_div(JNIEnv *env, jobject obj, jint a, jint b) {
+JNIEXPORT jint JNICALL Java_A3_div(JNIEnv *env, jobject obj, jint a, jint b) {  // Function for division
     if (b == 0) {
         printf("Error: Division by zero.\n");
         return 0; // Return 0 or handle error appropriately

Codes/Group A/Assignment-A3/A3.java

@@ -1,29 +1,48 @@
-import java.io.*;
+// Importing basic stuff
-import java.util.*;
+import java.io.*; // Used for I/O operations
+import java.util.*; // Contains basic utilities
 
 class A3 {
+  // Class name has to be same as file name for Java
+
   static {
+    // Used for loading the .so (on Linux) or .dll (on Windows) file when running
+    // This is the main so called "dynamic library"
     System.loadLibrary("A3");
   }
 
-    private native int add(int a, int b);
+  // Function declaration
-    private native int sub(int a, int b);
+  // private indicates the function is private, duh!
-    private native int mult(int a, int b);
+  // Use of native indicates the function body will be written in a language other than Java, such as C/C++
-    private native int div(int a, int b);
+  private native int add(int a, int b); // For addition
+  private native int sub(int a, int b); // For subtraction
+  private native int mul(int a, int b); // For multiplication
+  private native int div(int a, int b); // For division
 
-    public static void main(String[] args) {
+  public static void main(String[] args) { // the main function
-        Scanner sc = new Scanner(System.in);
+    Scanner sc = new Scanner(System.in); // For taking input
-        int a, b, ch;
 
-        System.out.println("\nEnter value of a : ");
+    int a, b;// Declaring variables for calculation
+    int choice = 0; // Declaring variable for switch-case
+
+    // Take input for a and b values
+    System.out.print("\nValue of a:\t");
     a = sc.nextInt();
-        System.out.println("\nEnter value of b : ");
+    System.out.print("\nValue of b:\t");
     b = sc.nextInt();
 
-        do {
+    // Main menu
-            System.out.println("\nENTER YOUR CHOICE : ");
+    while (true) {
-            ch = sc.nextInt();
+      System.out.println("----- MAIN MENU -----");
-            switch (ch) {
+      System.out.println("1 -> Addition");
+      System.out.println("2 -> Subtraction");
+      System.out.println("3 -> Multiplication");
+      System.out.println("4 -> Division");
+      System.out.println("5 -> Exit");
+      System.out.println("Choose an option:\t");
+      choice = sc.nextInt();
+
+      switch (choice) {
       	case 1:
           new A3().add(a, b);
           break;
@@ -31,15 +50,18 @@ class A3 {
 	  new A3().sub(a, b);
 	  break;
 	case 3:
-                    new A3().mult(a, b);
+	  new A3().mul(a, b);
 	  break;
 	case 4:
 	  new A3().div(a, b);
 	  break;
+	case 5:
+	  System.out.println("## END OF CODE");
+	  System.exit(0);
 	default:
-                    System.out.println("Your choice is wrong.");
+	  System.out.println("Please choose a valid option.");
-            }
+	  break;
-        } while (ch < 5);
+      }
+    }
   }
 }
-