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c++/Others/An implementation of Stack data structure.cpp

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+An implementation of Stack data structure
+
+#include <iostream>
+#include <new>
+#include <string>
+#include <sstream>
+using namespace std;
+
+#if !defined __STACK_H
+#define __STACK_H
+
+namespace stk{
+	class Stack{
+		private:
+			int *p;
+			int top,length;
+
+			string str()const;
+		public:
+			Stack();
+			Stack(const int);
+			Stack(const Stack&);
+			~Stack();
+
+			void push(int);
+			int pop();
+			int get_length()const;
+			bool is_empty()const;
+			Stack operator=(const Stack&);
+			friend ostream& operator<<(ostream&,Stack&);
+
+			class StackException{
+				private:
+					string desc;
+				public:
+					StackException(string exp){ desc="Exception : "+exp; }
+					string get_exp(){ return desc; }
+			};
+	};
+
+	Stack::Stack(){
+		top=-1;
+		length=0;
+		p=0;
+	}
+
+	Stack::Stack(const int size){
+		top=-1;
+		length=size;
+		try{
+			p=new int[length];
+		}catch(bad_alloc ba){
+			cout<<"Memory can not be alllocated
+";
+			return;
+		}
+	}
+
+	Stack::Stack(const Stack &o){
+		top=o.top;
+		length=o.length;
+		try{
+			p=new int[length];
+		}catch(bad_alloc ba){
+			cout<<"Memory allocation failed
+";
+			return;
+		}
+		for(int i=0;i<length;i++)
+			p[i]=o.p[i];
+	}
+
+	Stack::~Stack(){
+		if(p!=0)
+			delete [] p;
+	}
+
+	void Stack::push(int elem){
+		if(p==0){
+			try{
+				p=new int[1];
+			}catch(bad_alloc ba){
+				throw StackException("Memory fault
+");
+			}
+			length++;
+			top++;
+			p[top]=elem;
+		}
+		else if(top==(length-1)){
+			int *q;
+			try{
+				q=new int[length+1];
+			}catch(bad_alloc ba1){
+				throw StackException("Memory fault
+");
+			}
+			for(int i=0;i<length;i++)
+				q[i]=p[i];
+			length++;
+			top++;
+			q[top]=elem;
+			delete [] p;
+			p=q;
+		}
+		else{
+			top++;
+			p[top]=elem;
+		}
+	}
+
+	int Stack::pop(){
+		if(p==0 || top==-1){
+			throw StackException("Stack empty!
+");
+		}
+		int ret=p[top];
+		top--;
+		length--;
+
+		if(top==-1){
+			delete [] p;
+			p=0;
+		}
+		else{
+			int *q;
+			try{
+				q=new int[length];
+			}catch(bad_alloc ba){
+				throw StackException("Memory fault
+");
+			}
+			for(int i=0;i<length;i++)
+				q[i]=p[i];
+			delete [] p;
+			p=q;
+		}
+
+		return ret;
+	}
+
+	int Stack::get_length()const{
+		return length;
+	}
+
+	bool Stack::is_empty()const{
+		return ((p==0)? true : false);
+	}
+
+	string Stack::str()const{  // private member function
+		stringstream ss;
+		for(int i=0;i<length;i++){
+			ss << p[i];
+			if(i!=(length-1))
+				ss << ", ";
+		}
+		//ss<<"
+";
+		return ss.str();
+	}
+
+	Stack Stack::operator=(const Stack &stk){
+		length=stk.length;
+		top=stk.top;
+
+		if(p!=0)
+			delete [] p;
+		try{
+			p=new int[length];
+		}catch(bad_alloc ba){
+			throw StackException("Memory fault in copying!
+");
+		}
+		for(int i=0;i<length;i++)
+			p[i]=stk.p[i];
+
+		return *this;
+	}
+
+	ostream& operator<<(ostream &o,Stack &s){
+		o<<s.str();
+		return o;
+	}
+
+} // namespace stk;
+
+#endif
+
+