Calculation (computer) code of suffix expression

Ideas

The calculation of suffix expression is realized by stack
① Scan the next element from left to right , Until all the elements are processed
② If the operand is scanned, it is pushed onto the stack , And back to ①; Otherwise execution ③
③ If operator is scanned , Then two stack top elements pop up , Perform the corresponding operation , The operation result is pushed back to the top of the stack , go back to ①

#include <iostream>
#include <string.h>

using namespace std;

#define MaxSize 10

typedef struct{
    
    char data[MaxSize];// Static arrays hold the elements in the stack 
    int top;// To the top of the stack 
} SqStack;

void InitStack(SqStack &S){
    
    S.top = -1;// Initialize the stack top pointer 
    memset(S.data,'0', MaxSize);
}

bool StackEmpty(SqStack S){
    
    if(S.top==-1)// Empty stack 
        return true;
    else
        return false;
}

bool Push(SqStack &S,char x){
    
    if (S.top==MaxSize-1)
        return false;
    S.top += 1;
    S.data[S.top] = x;
    return true;
}

bool Pop(SqStack &S,char &x){
    
    if(S.top==-1)
        return false;
    x = S.data[S.top];
    S.top -= 1;
    return true;
}
// Determine character type 
int StrType(char c){
    
    if(isdigit(c)){
    
        return 1;
    }
    if(c=='('||c==')'){
    
        return 2;
    }
    if(c=='+'||c=='*'||c=='-'||c=='/'){
    
        return 3;
    }
    return 0;
}

char Calculate(char numa,char numb,char oper){
    
    int inta = numb - 48;
    int intb = numa - 48;
    switch (oper)
    {
    
        case '+':
            return (inta + intb) + 48;
            break;
        case '-':
            return (inta - intb) + 48;
            break;
        case '*':
            return (inta * intb) + 48;
            break;
        case '/':
            return (inta / intb) + 48;
            break;
        default:
            return '0';
            break;
    }
}


char HzCalculate(string str){
    
    SqStack S;
    InitStack(S);

    for (size_t i = 0; i < str.size(); i++)
    {
    
        char cur = str.at(i);
        int opt = StrType(cur);

        if(opt==1){
    
            Push(S, cur);
            continue;
        }

        if(opt==3){
    
            char numa, numb;
            Pop(S,numa);
            Pop(S, numb);
            char result = Calculate(numa, numb, cur);
            Push(S, result);
        }
    }

    char result;
    Pop(S, result);
    return result;
}

int main(int argc, char const *argv[])
{
    
    //"1+2*(4-3)-6/3"
    char res = HzCalculate("1243-*+63/-");
    cout << res << endl;
    return 0;
}