Infix to prefix to postfix converter.cpp

#include<bits/stdc++.h>
#define SIZE 5
using namespace std ;

class stackk
{
private:
    char data [50];
    int top;
public :
    stackk()
    {
        top=0;
    }
    void push(char item)
    {

        data [top]=item;
        top++;
    }
    char getTop()
    {
        return data[top-1];
    }
    char pop()
    {
        if(top==0)
            return '0';
        top--;
        char item=data[top];
        return item;
    }
    int isEmpty()
    {
        if (top==0)
            return 1;
        else
            return 0;
    }
    int getLength()
    {
        return top;
    }
};


void infix_postfix(char * str)
{
    stackk st;
    char temp[30];
    int j=-1;
    int size = strlen(str);

    for(int i=0; i<size; i++)
    {
        if(str[i]!='(' && str[i]!=')' && str[i]!='{' && str[i]!='}' && str[i]!='[' && str[i]!=']' && str[i]!='+' && str[i]!='-' && str[i]!='*' && str[i]!='/')
        {
            temp[++j] = str[i];
        }
        else if(str[i]=='+' || str[i]=='-')
        {
            st.push(str[i]);
        }
        else if(str[i]=='(')
        {
            st.push(str[i]);
        }
        else if(str[i]=='*' || str[i]=='/')
        {
            st.push(str[i]);
        }
        else if(str[i]==')')
        {
            while(1)
            {
                if(st.getTop()=='(')
                {
                    st.pop();
                    break;
                }
                temp[++j] = st.getTop();
                st.pop();
            }
        }
    }
    while(!st.isEmpty())
    {
        temp[++j] = st.getTop();
        st.pop();
    }
      

    int i=-1;
    for(j=0; j<size; j++)
    {
        str[++i]=temp[j];
    }
}

void reverse(char *exp)
{

    int n = strlen(exp);
    for (int i = 0; i < n / 2; i++)
        swap(exp[i], exp[n - i - 1]);
}
void brackets(char * exp)
{
    int n = strlen(exp);
    for (int i = 0; i <=n; i++)
    {
        if(exp[i]=='(')
            exp[i]=')';
        else if(exp[i]==')')
            exp[i]='(';
    }
}


void infix_prefix(char *exp)
{

    reverse(exp);
    brackets(exp);
    infix_postfix(exp);
    reverse(exp);

}

int main (void)
{
    while(1)
    {
        printf("1.Infix to Prefix.  2.Infix to POSTFIX.\n5.Exit\n");
        int ch;
        scanf("%d",&ch);
        if(ch==1)
        {
            char str[30];
            printf("Infix Expression : ");
            cin >> str;
            infix_prefix(str);

            printf("Prefix Expression : ");
            cout<<str;
            printf("\n");
        }
        else if(ch==2)
        {
            char exp[30];
            printf("Infix Expression : ");
            cin >> exp;

            infix_postfix(exp);
            printf("Postfix Expression : ");
            cout<<exp;
            printf("\n");
        }
        else if(ch==5)
            break;
    }
}