[Natsheh]

I'm trying to make a calculator that only support multipling , adding and subtraction with a specified synax

Synax will look alike the following :-

{ 5.0 + { { 5 * 5 } - { 3 * 4 } } }

Regex pattren : "^^.*\{.*\d+(?:.*\..*\d*).*[*+-].*\d+(?:.*\..*\d*).*\}.*$"

Now i'm real confused on how to turn that string (equation) to an answer.

[klippy]

Look into Shunting-yard algorithm and Postfix/Reverse Polish notation, that should help you.

[Natsheh]

Solved using regex

Fixed pattren : "^^.*(\{ *(\d+(?: *\. *\d* *| *))([\*\+\-]) *(\d+(?: *\. *\d* *| *))\}).*$"

Seems like I was missing brackets for string parsing.