4)Peng+Ning

using namespace std ;
 * 1) include
 * 2) include

class stack{ private : int top ; char Array [ 5 ]; bool Full ; bool Empty ;

public : stack{ top = 0 ;  Full = false ;  Empty = true ; } ~stack{}; bool Push( char a){ if ( Empty == true ){ Array [ 0 ]=a;  Empty = false ; top= 0 ;  return true ;}  else if ( Full == true ){ Array[ 4 ]=a;  return true ; }  else if ( Empty == false && Full == false ){ top ++;  Array [ top ]=a; if (top== 4 ) Full = true ;  return true ; } } char Pop{ if ( Empty == false && top >= 0 ){  Array [ top ]= 0 ; top --;  return true ;}  else return false ; }; bool IS_EMPTY{ if ( Empty == true ){  cout << "Stack is empty!" ;  return true ;}  else return false ; }; bool IS_FULL{ if ( Full == true ){  cout << "Stack is full!" ; <span style="color: rgb(0, 0, 0); white-space: pre;"> return true ;} <span style="color: rgb(0, 0, 0); white-space: pre;"> else return false ; }; };