First of all understand that CAPTCHA are not designed to be automated. The basic reason why CAPTCHAs were introduced was to keep automated programs/bots/spammers at bay. So if someone asks you to automate CAPTCHAs your answer should be "No, it's not possible". We do have roundabout ways but that's a topic in itself.
>>YES. I am using QTP 9.2. I also checked the Regular Expressions checker link which you have given but when I entered [0-9]{4,}[a-z]{4,}[A-Z]{4,} but it doesnt return "True". Please tell me what should I enter?
What is the test string?
>>Which Repository Parameter window should I select?
I mean should I select type, name or html tag?
where should I enter the value of Regular expression?
A parameter which has a dynamic value.
>>I also have another doubt. When I enter the value in the name(In Description Properties), suddenly a pop up window opens asking if \ is required. What should I select "Yes" or "No"?
\ is an escape character. It is used when a character used in regular expression needs to be used literally.
I would suggest you to go through the post on Regular Expressions in QTP (UFT) thoroughly and understand the concepts.
>>YES. I am using QTP 9.2. I also checked the Regular Expressions checker link which you have given but when I entered [0-9]{4,}[a-z]{4,}[A-Z]{4,} but it doesnt return "True". Please tell me what should I enter?
What is the test string?
>>Which Repository Parameter window should I select?
I mean should I select type, name or html tag?
where should I enter the value of Regular expression?
A parameter which has a dynamic value.
>>I also have another doubt. When I enter the value in the name(In Description Properties), suddenly a pop up window opens asking if \ is required. What should I select "Yes" or "No"?
\ is an escape character. It is used when a character used in regular expression needs to be used literally.
I would suggest you to go through the post on Regular Expressions in QTP (UFT) thoroughly and understand the concepts.