Is the operator legal?

//  Header file  # Include <Stdio. h> # Include <Malloc. h> # Define Maxsize 100 Typedef  Char  Elemtype; typedef  Struct  {Elemtype data [maxsize];  Int Top; /*  Stack pointer  */ } Sqstack;  /*  Sequence stack Type Definition  */  Void Initstack (sqstack *& S) {s = (Sqstack *) malloc ( Sizeof  (Sqstack); s -> Top =- 1  ;}  Void Clearstack (sqstack *& S) {free (s );}  Int Stacklength (sqstack *S ){  Return (S-> top + 1  );}  Int Stackempty (sqstack * S ){  Return (S-> Top =- 1  );}  Int Push (sqstack *& S, elemtype e ){  If (S-> Top = maxsize- 1 ) /* Stack Overflow  */                Return   0  ; S -> Top ++ ; S -> Data [S-> top] = E;  Return   1  ;}  Int Pop (sqstack * & S, elemtype & E ){  If (S-> Top =- 1 )/*  Stack is empty, that is, off-Stack Overflow  */                Return   0  ; E = S-> data [S-> Top]; S -> Top -- ;  Return   1  ;}  Int Gettop (sqstack * s, elemtype & E ){  If (S-> Top =- 1 ) /*  Stack is empty, that is, off-Stack Overflow  */                Return   0  ; E = S-> data [S-> Top];  Return   1  ;}  Void Dispstack (sqstack * S ){  Int  I;  For (I = s-> top; I> =0 ; I -- ) Printf (  "  % C  " , S-> Data [I]); printf (  "  \ N  "  );}  //  Implementation Functions  # Include <Iostream> # Include  "  Heshan1.h "  Using   Namespace  STD;  Int Judge ( Char  A []) {  Int  I; elemtype X; sqstack * S; initstack (s );  For (I = 0 ; A [I]! = '  \ 0  ' ; I ++){  If (A [I] = '  I  '  ) Push (s, A [I]);  Else   If (A [I] = '  O  '  ){  If (S-> Top =- 1 ) // When an "O" operation is performed, the system first checks whether the stack is empty. Otherwise, the operation continues.  {  Return   0  ;}  Else  Pop (S, x );}}  Return (S-> Top =- 1  );}  Void  Main (){  Char A [ 20 ]; Int  I;  For (I = 0 ; I < 20 ; I ++ ) {A [I] = '  \ 0  '  ;} Cout < "  Enter operation sequence (I, O sequence)  " < Endl; CIN >A;  Int M = Judge ();  If (M = 0  ) Cout < "  The operation sequence you entered is invalid.  " < Endl;  Else  Cout < "  The operation sequence you entered is legal  " <Endl ;}