few days ago i asked a question here about how to convert *infix to prefix* and someone was nice enough to answer it but they answered *infix to postfix*. in the book which i am using(i believe it’s a translation of modern compiler design by dick grune) it give’s the required grammers:

```
(1) expr -> expr + term | expr – term | term
(2) term -> term * factor | term / factor | factor
(3) factor -> digit | (expr)
(4) digit -> 0 | 1 | 2 | …| 9
```

**we are not allowed to use the stack method which is used in data structure.**

infix

9-5+2

and we should get

+-952

Source: Windows Questions C++