why i need to use semi colon??? can't i use any other punctuation mark???

Answer 1

every language has it's syntax, it's mandatory to follow the right syntax, if not the compiler can't translate the code... programming follows rigid rules, that's because every code is translated into binary that means an algorithm for a computer.

Answer 2

The syntax of C++ demands a semicolon - either you acceot the rules or it will not compile.
On the road you also have to obey the traffic rules or you will be punished :)

in some cases you can also use a comma , - but be careful, you combine the commands to a sequence.