Informatica Scenario : Remove special character from the string

Senario:

Suppose  in flat_file  some special symbols like @,%,$,#,&  has added in empno column along with the actual data. How to  remove those special charcters ? ( see article , on how to remove $ from salary )

example:  empno in source   

empno(in string format)

7@3%$,21432#@1324&*,$2

In target :empno

7321
4321
3242

Following are the steps for achieving this mapping :  

1. Connect 0/p columns of SQF to an expression transformation.
2. In expression make empno as input and create another port empno1 as output port with date datatype. 
3. And in empno1 write condition like this. and finally send it to target.

Your comments and suggests keeps me going, don't forget to do so.