如何在正则表达式ColdFusion中允许空字符串？

Question

I have done my regular expression in JavaScript and my regex allows alpha characters, numbers, space and empty string. i would like the same regular expression in ColdFusion. I have everything working fine but empty string. Here is my JavaScript:

/^([A-Z0-9 ]{1,50})?$/i

and here is what I have in ColdFusion:

<cfset match = REMatch("^[A-Za-z0-9 ]{1,50}$",myText)> 

this will match everything I want but empty string. I can not use ? in ColdFusion because that will look to match any character in the string. If anyone knows how to match an empty string please let me know. Thanks.

Answer 1

Set the min value to 0

<cfset match = REMatch("^[A-Za-z0-9 ]{0,50}$",myText)>
                                      ^

The limiting quantifier allows setting both thresholds, min and max. When you set the min value to 0, it will allow matching nothing, empty string.

Pattern details :

• ^ - start of string
• [A-Za-z0-9 ]{0,50} - 0 to 50 ASCII letters, digits or spaces
• $ - end of string.