POJ 3295 constructs a stack to evaluate the value of an expression

Approximate test instructions:

Enter a logical expression consisting of 10 letters of P, Q, R, S, T, K, A, N, C, E,

where P, Q, R, S, T value is 1 (true) or 0 (false), that is, the logical variable;

K, A, N, C, E are logical operators,

K--and:x && y

A--Or:x | | Y

N--not:!x

C--implies: (!x) | | Y

E--Equals:x==y

Ask if this logical expression is a perpetual truth.

#include <iostream> using namespace std;
 int count=0; struct Stack {int value;}
STACK[101]; int N (int x) {return!x;} int E (int x,int y) {return x==y;} int C (int x,int y) {return (!x) | |
Y } int K (int x,int y) {return x&&y;} int A (int x,int y) {return x| |
Y
	} void Insert (int num) {stack[count].value=num;
count++;
	} int Pop () {int x;
	X=stack[count-1].value;
	count--;
return x;
		} bool Isvalue (char ch,int p,int q,int r,int s,int t) {switch (ch) {case ' P ': Insert (P);
	return true;
		Case ' Q ': Insert (q);
	return true;
		Case ' R ': Insert (R);
	return true;
		Case ' s ': Insert (s);
	return true;
		Case ' t ': Insert (t);
	return true;
} return false;
	} void Compute (char ch) {int x, y;
		Switch (CH) {case ' K ': X=pop ();
		Y=pop ();
		Insert (K (x, y));
	Break
		Case ' A ': X=pop ();
		Y=pop ();
		Insert (A (x, y));
	Break
		Case ' C ': X=pop ();
		Y=pop ();
		Insert (C (x, y));
	Break
		Case ' E ': X=pop ();
		Y=pop ();
		Insert (E (x, y));
	Break
Case ' N ': X=pop ();		Insert (N (x));
	Break
	}} int main (int argc,char *argv[]) {char wff[101];
	int length,i;
	int p,q,r,s,t;
	int end;
	BOOL Flag;
	memset (stack,0,sizeof (stack));
		while (cin>>wff&&wff[0]!= ' 0 ') {length=strlen (WFF);
		Flag=true;
						for (p=0;p<=1;p++) {for (q=0;q<=1;q++) {for (r=0;r<=1;r++) {for (s=0;s<=1;s++) {
							for (t=0;t<=1;t++) {i=length-1;
								while (i>=0) {if (!isvalue (wff[i],p,q,r,s,t)) {compute (wff[i]);
							} i--;
							} End=stack[count-1].value;
							count--;
								if (!end) {flag=false;
							Break
		}}}}} if (flag==true) {cout<< "tautology" <<endl;
		} else {cout<< "not" <<endl;
}} return 0; }