please help me in this code

HELLO EVERY ONE
HOW ARE YOU?
i want you to help me please
i have question and i am try to solve it
but when put my code in compiler is not work
i really need help
the question is

Write a program that reads a string of arithmetic expression from the keyboard, and evaluates the arithmetic operation in the string. Your program should accept only
• Positive Real or Integer Numbers
• The four basic arithmetic operators, +, -, *, /
• Circle parenthesis ( , )
we want me use stack to solve it
Here some examples about how your program should work:

2 - 3 * 4 + 2 -8
(5 + (11-5) * 2) * 4 + 9.9 77.9
2 + 3 = 5 Error: Undefined symbol '='
(5 + (11-5 * 2) * 4 + 9 Error: Missing parenthesis ')'
7* (8-2)) Error: Missing parenthesis '('
6*3e9 Error: Undefined symbol 'e'
2/[7+5] Error: Undefined symbol '[',’]’
my try code is

Code:

#include <iostream>
#include "hyjh.h"
using namespace std;
 
 string ab ;
 	  Stack <string> stack;
 void read()
 {
 	cout<<"enter the equation";
 	getline(cin,ab);
 }
 
 void check()
 {
  for(int i=1;i < ab.length();i++)
   {
   if  if(ab[i]<=9 || ab[i]>=0 ||ab[i]=='+'||ab[i]=='*')
   {
   	if(ab[i] == "*")
   	{
   	cout<<"true";
   	}
   	else 
   	cout<<"false";
   	
   }
   }
 }
 
void parnt()
{
	for(int i=1;i < ab.length();i++)
	{
		if(ab[i]=="(")
		{
		stack.pushstack(ab[i]);
		}
		if(ab[i]==")")
		{
		if( stack.emptystack())
		{
			cout<<"the stack empty";
			else
			
			stack.popstack(ab[i]);
		}
		}
		if (!stack.emptystack())
		{
			cout<<"opening parenthesis not match";
		}
	}
}
void postfix()
{
	for(int i=1;i < ab.length();i++)	{
		if(ab[i]=="(")
		{
		stack.pushStack(ab[i]);
		}
		else
		if(ab[i]==")")
		{
			stack.popStack(ab[i]);
			while(ab[i] !="(")
			{
				stack.popStack(ab[i]);
			}
		}
		else 
		if(ab[i]=="+"||"*"||"/"||"-")
		{
			stack.stacktop(ab[i]);
			if(stack.stacktop(ab[i])=="*"||"/" && ab[i] =="+"||"-" )
			{
					stack.popstack(ab[i]);
			}
			else 
			if(stack.stacktop(ab[i])=="+"||"-" && ab[i] =="*"||"/")
			{
				stack.pushstack(ab[i]);
			}
	
      	else 
         if (stack.stacktop(ab[i])==  ab[i])
         {
         		stack.popstack(ab[i]);
         }
		}
		while(!stack.emptystack())
		{
				stack.popstack(ab[i]);
		}
		
	}
}
	void eval()
{
	int val;
	 
		for(int i=0;i!='\0';i++)
	{
	
		if(ab[i]>=0 || ab[i]<=9)
		{
			stack.pushstack(ab[i]);
		}
		else 
		if(ab[i] == "+" )
	{
		stack.popstack(ab[i]);
		stack.popstack(ab[i]);
		val= ab[i] + ab[i] ;
		stack.pushstack(val);
	}
	else
	if(ab[i] == "-")
	{
		stack.popstack(ab[i]);
		stack.popstack(ab[i]);
		val= ab[i] - ab[i] ;
		stack.pushstack(val);
	}
	else
	if(ab[i] == "*")
	{
		stack.popstack(ab[i]);
		stack.popstack(ab[i]);
		val= ab[i] * ab[i] ;
		stack.pushstack(val);
	}
		else
	if(ab[i] == "/")
	{
		stack.popstack(ab[i]);
		stack.popStack(ab[i]);
		val= ab[i] / ab[i] ;
		stack.pushstack(val);
	}
	}
	stack.popStack(ab[i]);
}	
}
 	int main()
 	{
 		 
 	 	 
 	 read();
 	 check();
 	 postfix();
 	 eval();
 	 return 0;
 	}

You haven't asked a question, you've just posted the assignment details.
You need to give far better information than "compiler is not work" [sic].
You need to state exactly what the problem is, with exact error messages.