Data update

Task/Stack/REXX/stack.rexx

@@ -0,0 +1,42 @@
+/* REXX ***************************************************************
+* supports push, pull, and peek
+* 11.08.2013 Walter Pachl
+**********************************************************************/
+stk.=0
+Call push 123                  /*pushes   123   onto the stack.        */
+Say empty()
+say peek()
+say pull()                     /*pops last value stacked & removes it. */
+Say empty()
+say peek()
+say push(456)
+say peek()
+Exit
+
+push: Procedure Expose stk.
+  Parse Arg v
+  z=stk.0+1
+  stk.z=v
+  stk.0=z
+  Return v
+
+peek: Procedure Expose stk.
+  If stk.0=0 Then
+    Return 'stack is empty'
+  Else Do
+    z=stk.0
+    Return stk.z
+    End
+
+pull: Procedure Expose stk.
+  If stk.0=0 Then
+    Return 'stack is empty'
+  Else Do
+    z=stk.0
+    res=stk.z
+    stk.0=stk.0-1
+    Return res
+    End
+
+empty: Procedure Expose stk.
+  Return stk.0=0