Parenthesized Expression (Infix and Post fix) Conversion and Evaluation - c++

Question

I have the below code working fine but outputs only 2nd input, not 1st or 3rd.
My code should get fully parenthesized expression from console and convert it to postfix expression and then that postfix expression should be evaluated in modulo 10.Therefore, all results (including intermediate results) are single decimal digits in {0, 1, …, 9}. I need to store only single digits in the stack.
My inputs and outputs are shown in below.I only got 2nd input correctly.
Please advise.
Expression 1: (((2+(5^2))+7)
Answer:
252^+7+
4 in modulo 10
Expression 2: ((((2+5)*7)+((9*3)*2))^2)
Answer:
25+7*93*2*+2^
9 in modulo 10
Expression 3: ((((2*3)*(4*6))*7)+(((7+8)+9)*((2+4)*((7+8)+9))))
Answer:
23*46*7*789++24+78+9+**+
4 in modulo 10
My code:
#include <iostream>
#include <string>
#include<sstream>
using namespace std;
class STACK {
private:
char *s;
int N;
public:
STACK(int maxN) {
s = new char[maxN];
N = 0;
}
int empty() const {
return N == 0;
}
void push(char item) {
s[N++] = item;
}
char pop() {
return s[--N];
}
};
int main() {
string infixExpr;
string postfixExpr = "";
cout << "Enter infix expression:" << endl;
cin >> infixExpr; //converting to postfix read from the input
int N = infixExpr.size(); //strncpy(a, infixExpr.c_str(), N);
STACK ops(N);
char ch;
for (int i = 0; i < N; i++) {
if (infixExpr[i] == ')')
{
ch = ops.pop();
postfixExpr.push_back(ch);
}
if ((infixExpr[i] == '+') || (infixExpr[i] == '*') || (infixExpr[i] == '^'))
ops.push(infixExpr[i]);
if ((infixExpr[i] >= '0') && (infixExpr[i] <= '9'))
{
//cout << infixExpr[i] << " ";
postfixExpr.push_back(infixExpr[i]);
}
}
cout <<"Answer :"<<endl;
cout <<postfixExpr <<endl; //evaluate post fix expression
N = postfixExpr.size();
STACK save(N);
int result;
int num;
int count = 0;
string temp = "";
for (int i = 0; i < N; i++) {
// cout << " Expr[i] " << postfixExpr[i] << endl;
if (postfixExpr[i] == '+')
save.push((save.pop() + save.pop()) % 10);
if (postfixExpr[i] == '*')
save.push((save.pop() * save.pop()) % 10);
if (postfixExpr[i] == '^') {
count = save.pop() - '0';
num = save.pop() - '0'; //cout << result << "- " <<"-" <<count<<endl;
result = 1;
for(int j = 1; j <= count; j++)
{
result = result * num;
result = result % 10;
}
stringstream convert;
convert << result;//add the value of Number to the characters in the stream
temp = convert.str();//set Result to the content of the stream
save.push(temp[0]);
}
if ((postfixExpr[i] >= '0') && (postfixExpr[i] <= '9'))
{
save.push(postfixExpr[i]);
}
}
cout << save.pop() <<" in module 10"<< endl;
return 1;
}