diff --git a/C++/Maximum_Subarray_Sum.cpp b/C++/Maximum_Subarray_Sum.cpp
index 20975833..092dc56e 100644
--- a/C++/Maximum_Subarray_Sum.cpp
+++ b/C++/Maximum_Subarray_Sum.cpp
@@ -3,7 +3,15 @@
 #include <vector>
 
 using namespace std;
+int maxSubarraySum(vector<int> nums, int n){
+    int best = 0, sum = 0;
+    for(int i = 0; i < n; i++) {
+        sum = max(nums[i], sum + nums[i]);
+        best = max(best, sum);
+    }
+    return best;
 
+}
 int main() {
     int n;
     cin >> n;
@@ -12,13 +20,8 @@ int main() {
     for(int i = 0; i < n; i++)
         cin >> nums[i];
 
-    int best = 0, sum = 0;
-    for(int i = 0; i < n; i++) {
-        sum = max(nums[i], sum + nums[i]);
-        best = max(best, sum);
-    }
-
+    int best =maxSubarraySum(nums,n);
     cout << best << endl;
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/C++/Program to reverse number.cpp b/C++/Program to reverse number.cpp
index ea69a3e4..80c7bd96 100644
--- a/C++/Program to reverse number.cpp	
+++ b/C++/Program to reverse number.cpp	
@@ -1,5 +1,6 @@
 #include <iostream>  
 using namespace std;  
+//reverse function
 int reverseNum(int n){
 int reverse=0,rem;
   while(n!=0)    
diff --git a/Useful-Books/C++/CP handbook.pdf b/Useful-Books/C++/CP handbook.pdf
new file mode 100644
index 00000000..ab4448e3
Binary files /dev/null and b/Useful-Books/C++/CP handbook.pdf differ