add Stack input

Stack/Stack.cc

@@ -0,0 +1,57 @@
+#include <iostream>
+using namespace std ;
+
+const int LEN = 80 ; // default stack length
+
+struct Stack {
+  // Implementation
+  double s[LEN] ;
+  int count ;
+
+  // Interface
+  void init() { count = 0 ; }
+  int nitems() { return count ; }
+  bool full() { return (count==LEN) ; }
+  bool empty() { return (count==0) ; }
+
+  void push(double c) { 
+    if (full()) {
+      cout << "Stack::push() Error: stack is full" << endl ;
+      return ;
+    }
+    s[count++] = c ;
+  }
+  
+  double pop() { 
+    if (empty()) {
+      cout << "Stack::pop() Error: stack is empty" << endl ;
+      return 0 ;
+    }    
+    return s[--count] ;
+  }
+} ;
+
+
+int main() {
+  
+  Stack s ;
+  s.init() ; // initialize Stack
+  
+  // Write doubles into Stack
+  int i ;
+  for (i=0 ; i<10 ; i++) {
+    cout << "pushing value " << i*i << " in stack" << endl ;
+    s.push(i*i) ;
+  }
+  
+  // Count doubles in fifo
+  cout << s.nitems() << " value in stack" << endl ;
+  
+  // Read doubles back from fifo
+  while (!s.empty()) {
+    double val = s.pop() ;
+    cout << "popping value " << val << " from stack" << endl ;
+  }
+
+  return 0 ;
+}