diff --git a/.github/workflows/validate_new_filenames.yml b/.github/workflows/cpplint_modified_files.yml
similarity index 60%
rename from .github/workflows/validate_new_filenames.yml
rename to .github/workflows/cpplint_modified_files.yml
index f201829da..d1d850c1d 100644
--- a/.github/workflows/validate_new_filenames.yml
+++ b/.github/workflows/cpplint_modified_files.yml
@@ -1,21 +1,34 @@
-name: validate_new_filenames
+name: cpplint_modified_files
 on: [push, pull_request]
 jobs:
-  validate_new_filenames:
+  cpplint_modified_files:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
+      - uses: actions/setup-python@v1
+      - run: python -m pip install cpplint
       - run: git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY
       - run: git diff origin/master --name-only > git_diff.txt
-      - name: Validate new filenames
+      - name: cpplint_modified_files
         shell: python
         run: |
           import os
+          import subprocess
           import sys
-          print(sys.version_info)  # legacy Python :-(
+
+          print("Python {}.{}.{}".format(*sys.version_info))  # legacy Python :-(
           with open("git_diff.txt") as in_file:
-            cpp_files = sorted(line.strip() for line in in_file
-                               if line.strip().lower().endswith(".cpp"))
+            modified_files = sorted(in_file.read().splitlines())
+          print("{} files were modified.".format(len(modified_files)))
+
+          cpp_exts = tuple(".c .c++ .cc .cpp .cu .cuh .cxx .h .h++ .hh .hpp .hxx".split())
+          cpp_files = [file for file in modified_files if file.lower().endswith(cpp_exts)]
+          print("{} C++ files were modified.".format(len(cpp_files)))
+          if not cpp_files:
+            sys.exit(0)
+
+          print("cpplint:")
+          print(subprocess.check_output(["cpplint"] + cpp_files).decode("utf-8"))
 
           upper_files = [file for file in cpp_files if os.path.basename(file) != os.path.basename(file).lower()]
           if upper_files:
diff --git a/Others/Happy_number.cpp b/Others/happy_number.cpp
similarity index 53%
rename from Others/Happy_number.cpp
rename to Others/happy_number.cpp
index f1b100810..7d25a1bbd 100644
--- a/Others/Happy_number.cpp
+++ b/Others/happy_number.cpp
@@ -1,19 +1,18 @@
 /* A happy number is a number whose sum of digits is calculated until the sum is a single digit,
   and this sum turns out to be 1 */
-#include <iostream>
-using namespace std;
 
-int main()
-{
+// Copyright 2019 TheAlgorithms contributors
+
+#include <iostream>
+
+int main() {
   int n, k, s = 0, d;
-  cout << "Enter a number:";
-  cin >> n;
+  std::cout << "Enter a number:";
+  std::cin >> n;
   s = 0;
   k = n;
-  while (k > 9)
-  {
-    while (k != 0)
-    {
+  while (k > 9) {
+    while (k != 0) {
       d = k % 10;
       s += d;
       k /= 10;
@@ -22,8 +21,8 @@ int main()
     s = 0;
   }
   if (k == 1)
-    cout << n << " is a happy number" << endl;
+    std::cout << n << " is a happy number" << std::endl;
   else
-    cout << n << " is not a happy number" << endl;
+    std::cout << n << " is not a happy number" << std::endl;
   return 0;
 }