Question

Hello

I keep getting this error Case value is not a constant expression for a lot of my cases like the one case(operand(expire[I])) Am I not supposed to do a function call in the case? Thank you.

for (int i=0; i<expr.length(); i++)

{

  switch(expr[i])

{

  case (operand(expr[i])):

valStack.push(expr[i]);

  break;

  case expr[i]=='(':

opStack.push(expr[i]);

  case opera(expr[i]):

  if (opStack.empty())

opStack.push(expr[i]);

  else if (precedence(expr[i])>precedence(opStack.top()))

opStack.push(expr[i]);

  else

{

  while (!opStack.empty() && precedence(expr[i]<=precedence(opStack.top())))

execute(valStack, opStack);

   opStack.push(expr[i]);

}

  break;

  case expr[i]==')':

  while (opStack.top()!='(')

{

execute(valStack, opStack);

result=valStack.top();

}

  

}

}

  return 0;

} // end processExpression

Answer 1

First thing you have to know is compiler needs the expression to be known at compile time to compile a switch and yes are obviously right, you are not supposed to do function call in case statement because the return value of the function is not known at compile time.

So the solution for this is simple: Convert the switch statement into an if-else statement.