Create reverse_string_using_stack.cpp

This is regarding the issue rathoresrikant#576 
Used a simple linked list based stack implementation.

Author: mhdshameel

Data Structures/Stacks/reverse_string_using_stack.cpp

@@ -0,0 +1,106 @@
+#include <iostream>
+#include <string>
+
+struct node
+{
+public:
+	char data;
+	node * next;
+
+	node(char data_t)
+	{
+		data = data_t;
+		next = NULL;
+	}
+	node()
+	{
+		next = NULL;
+	}
+};
+
+//simpe stack implementation using single linked list
+class stack_char
+{
+private:
+	int count;
+public:
+	node* head;
+	stack_char()
+	{
+		head = NULL;
+		count = 0;
+	}
+
+	void push(char data) 
+	{
+		node* new_node = new node(data);
+		if (!new_node)
+		{
+			std::cout << "new failed "<<std::endl;
+			return;
+		}
+		new_node->next = head;
+		head = new_node;
+		count++;
+	}
+
+	void pop() 
+	{
+		if (head == NULL) {
+			return;
+		}
+		node* temp = head;
+		head = head->next;
+		delete temp;
+		count--;
+	}
+
+	char top() 
+	{
+		return head->data;
+	}
+
+	bool isEmpty() {
+		return count == 0;
+	}
+
+	int size() {
+		return count;
+	}
+
+	//to be sure there is no memory leaks
+	~stack_char()
+	{
+		if (!isEmpty())
+		{
+			for (int i = 0; i<size(); i++)
+			{
+				pop();
+			}
+		}
+	}
+};
+
+std::string reverse_string(std::string to_be_reversed)
+{
+	stack_char stack;
+	std::string reversed = "";
+	for (char c : to_be_reversed)
+	{
+		stack.push(c);
+	}
+
+	int original_stack_size = stack.size(); //save this before itself, as in pop the stack size keeps reducing
+	for (int i = 0; i < original_stack_size; i++)
+	{
+		reversed.push_back(stack.top());
+		stack.pop();
+	}
+	return reversed;
+}
+
+int main()
+{
+	std::cout << reverse_string("Here is a string");
+	return 0;
+}