Ex 3.2: Dynamic Stack

Stack/Stack.cc

@@ -5,7 +5,8 @@
 void Stack::push(double c) {
 	if (full()) {
 		std::cout << "Stack::push() Error: stack is full" << std::endl ;
-		return ;
+
+		grow( DELTA );
 	}
 	s[count++] = c ;
 }
@@ -24,3 +25,26 @@ void Stack::inspect() {
 		std::cout << i << ": " << s[i] << std::endl;
 	}
 }
+
+void Stack::init( int in_size ) {
+	bufsize = in_size ;
+	count = 0 ;
+
+	s = new double[in_size];
+}
+void Stack::grow( int delta ) {
+	std::cout << "Growing by " << delta << std::endl;
+	double* newbuf = new double[ bufsize + delta ];
+
+	// Copy elements
+	for ( int i=0; i < count ; i++ )
+	{
+		newbuf[i] = s[i];
+	}
+
+	// Delete old Stack
+	delete[] s;
+
+	// Assign pointer
+	s = newbuf;
+}

Stack/Stack.hh

@@ -3,25 +3,32 @@
 #ifndef STACK_H
 #define STACK_H
 
-const int LEN = 80 ; // default stack length
+const int DELTA = 5 ; // default growing size
 class Stack {
 	// Interface
 	public:
-		Stack() { init(); }
-		~Stack() {}
+		Stack() { init( DELTA ); }
+		Stack( int in_size ) { init(in_size); }
+		~Stack() {
+			delete[] s;
+		}
 		int  nitems() { return count ; }
-		bool full() { return (count==LEN) ; }
+		bool full() { return (count==bufsize) ; }
 		bool empty() { return (count==0) ; }
 
 		void push( double c );
 		double pop();
 		void inspect();
 
+		void grow( int delta );
+
 	// Implementation
 	private:
-		void init() { count = 0 ; }
-		double s[LEN] ;
+		void init( int in_size );
+
+		double* s ;
 		int count ;
+		int bufsize ;
 
 };
 #endif

ex3.2/Stack.cc

@@ -0,0 +1,50 @@
+//Stack.cc
+#include <iostream>
+#include "Stack.hh"
+
+void Stack::push(double c) { 
+	if (full()) {
+		std::cout << "Stack::push() Error: stack is full" << std::endl ;
+		
+		grow( DELTA );
+	}
+	s[count++] = c ;
+}
+
+double Stack::pop() { 
+	if (empty()) {
+		std::cout << "Stack::pop() Error: stack is empty" << std::endl ;
+		return 0 ;
+	}		
+	return s[--count] ;
+}
+
+void Stack::inspect() {
+	for ( int i = nitems() - 1; i >= 0; i-- )
+	{
+		std::cout << i << ": " << s[i] << std::endl;
+	}
+}
+
+void Stack::init( int in_size ) { 
+	bufsize = in_size ;
+	count = 0 ;
+
+	s = new double[in_size];
+}
+void Stack::grow( int delta ) {
+	std::cout << "Growing by " << delta << std::endl;
+	double* newbuf = new double[ bufsize + delta ];
+
+	// Copy elements
+	for ( int i=0; i < count ; i++ )
+	{
+		newbuf[i] = s[i];
+	}
+
+	// Delete old Stack
+	delete[] s;
+
+	// Assign pointer
+	s = newbuf;
+}

ex3.2/Stack.hh

@@ -0,0 +1,34 @@
+//Stack.h
+
+#ifndef STACK_H
+#define STACK_H
+
+const int DELTA = 5 ; // default growing size
+class Stack {
+	// Interface
+	public:
+		Stack() { init( DELTA ); }
+		Stack( int in_size ) { init(in_size); }
+		~Stack() {
+			delete[] s;
+		}
+		int  nitems() { return count ; }
+		bool full() { return (count==bufsize) ; }
+		bool empty() { return (count==0) ; }
+
+		void push( double c );
+		double pop();
+		void inspect();
+		
+		void grow( int delta );
+
+	// Implementation
+	private:
+		void init( int in_size );
+
+		double* s ;
+		int count ;
+		int bufsize ;
+	
+};
+#endif

ex3.2/main.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+#include "Stack.hh"
+
+/*
+ * Dynamically Sized Stack Implementation
+ */
+using namespace std ;
+
+int main() {
+	Stack s(10) ;// initialize Stack
+	
+	// Write doubles into Stack
+	int i ;
+	for (i=0 ; i<15 ; i++) {
+		cout << "pushing value " << i*i << " in stack" << endl ;
+		s.push(i*i) ;
+	}
+
+	// Count doubles in fifo
+	cout << s.nitems() << " value in stack" << endl ;
+
+	cout << "Inspect the FIFO" << endl;
+	s.inspect();
+	
+	
+	// Read doubles back from fifo
+	while (!s.empty()) {
+		double val = s.pop() ;
+		cout << "popping value " << val << " from stack" << endl ;
+	}
+	
+	cout << "Inspect the FIFO" << endl;
+	s.inspect();
+	return 0 ;
+}