style: rename stack.h to stack.hpp

data_structures/stack.hpp

@@ -1,10 +1,10 @@
 /**
- * @file stack.h
+ * @file stack.hpp
  * @author danghai
  * @brief  This class specifies the basic operation on a stack as a linked list
  **/
-#ifndef DATA_STRUCTURES_STACK_H_
-#define DATA_STRUCTURES_STACK_H_
+#ifndef DATA_STRUCTURES_STACK_HPP_
+#define DATA_STRUCTURES_STACK_HPP_
 
 #include <cassert>
 #include <iostream>
@@ -153,4 +153,4 @@ class stack {
     int size;             ///< size of stack
 };
 
-#endif  // DATA_STRUCTURES_STACK_H_
+#endif  // DATA_STRUCTURES_STACK_HPP_

data_structures/test_stack.cpp

@@ -1,6 +1,6 @@
 #include <iostream>
 
-#include "./stack.h"
+#include "./stack.hpp"
 
 int main() {
     stack<int> stk;

data_structures/test_stack_students.cpp

@@ -14,7 +14,7 @@
 #include <iostream>
 #include <string>
 
-#include "./stack.h"
+#include "./stack.hpp"
 
 int main(int argc, char* argv[]) {
     double GPA;