Can you find the error, please, and tell me how to fix it

Question

https://code.sololearn.com/c2c4GTBjide5/?ref=app

Answer 1

Define variable answer out of switch.
https://www.sololearn.com/compiler-playground/cACVsrdDTDTk

Answer 2

If you must define and use a variable in `switch` labels, then wrap the label body inside curly brackets.

However, in your case, it would be simpler to define variable <result> once before the `switch` and then just use it inside the labels.

switch( math )
{
case '+':
{
// code here ...
}
}