You can add checkpoints while creating or editing your QTP test script. It is generally more convenient to define checkpoints after creating the initial test.
To add new checkpoints while editing or recording your test: Use the commands in the Insert > Checkpoint menu, or click the Insert Checkpoint button  in the toolbar. This displays a menu of checkpoint options that are relevant to the selected step.
To add new checkpoints while editing only:

Right-click the step where you want to add the checkpoint and select the relevant checkpoint option.
Select the step …

In QTP, there are multiple ways to create Regular Expressions. Below are most common 15 different ways to create Regular Expressions:
1. Using the Backslash Character: A backslash (\) can serve two purposes. It can be used in conjunction with a special character to indicate that the next character be treated as a literal character. For example, \. would be treated as period (.) instead of a wildcard. Alternatively, if the backslash (\) is used in conjunction with some characters that would otherwise be treated as literal …

Before start writing the main post, I would like to tell you first that in QTP, you can use regular expressions only for values of type string.
In QTP, you can define a regular expression for a constant value, a Data Table parameter value, an Environment parameter value, or a property value in a programmatic description.
You can define a regular expression by entering the regular expression syntax for the string in the Value box in the Constant Value Options dialog box or the Parameter Options dialog box. …

You can use a formula in a checkpoint to confirm that an object created on-the-fly or another variable object in your Web page or application contains the value it should for a given context. For example, suppose a shopping cart Web site displays a price total. You can create a text checkpoint on the displayed total value and use a Data Table formula to check whether the site properly computes the total, based on the individual prices of the products selected for purchase in …

You can use Microsoft Excel formulas in your Data Table of QTP. This enables you to create contextually relevant data during the test run session in QTP. You can also use formulas as part of a checkpoint to check that objects created on-the-fly (dynamically generated) or other variable objects in your Web page or application have the values you expect for a given context.
When you use formulas in a Data Table to compare values (generally in a checkpoint), the values you compare must be of …