how to concatenate these two regular expression in one

[nghiemthanh]

I am using regular expression validation in asp.net and have two regular expressionsFirst is to prevent special characters\[code\][A-Za-z0-9_]+\[/code\]Second is to validate min max range\[code\](\s|.){6,15}\[/code\]I want to merge these tow in one validation expression, please suggest me how I can do it