Easy way to automate testing

QTP VBScript contains different niceties. This article shows that 1 + 1 doesn't equal 2 sometimes.

Exactly, 1 + 1 doesn't equal 2 sometimes.

Well, I've prepared this QTP script:

I will explain it step by step and show all entered data and generated result.

1. Read first number from user's input
   I enter 1 as a first number:
   
   
2. Read second number from user's input
   I enter 2 as a second number:
   
   
3. Increase first number by 1
   
   n1increased = n1 + 1
   
   
   
4. Check whether first increased number equals to second number
   
   If n1increased = n2 Then
       MsgBox n1 & " + 1 equals " & n2
   Else
       MsgBox n1 & " + 1 doesn't equal " & n2
   End If
   
   And the result is:
   

Do you know why it is so? What is a reason?
The answer is simple. This is due to converting of VBScript types.

After you read first number (1) from user and assign it (value of course value, not user :) ) to variable, this variable has value of String type.
So, this is the same like n1 = "1"

When VBScript executes this line:
it sees, that we perform mathematical operation and converts n1 into number.
Then VBScript calculates n1 + 1 and the result (2) has a numeric type - Double (special double-precision floating-point value).

Here is the main point! 2 as Number is not the same as 2 as String. These values have different type and that's why they differ.
Simple visual example - two apples are not equal to two pears :)

I can demonstrate the above types converting.
I've added this code into our QTP script before if-then-else:
And its result is:
That's why the value of number variable is not equal to the value of string variable.


Well, How to make that 1 + 1 = 2 ?
Answer: Convert string value to number with CInt function:
And the result is:
It works. It works correctly :)

I hope, you will keep in mind this issue with VBScript types converting. It can save your time during debugging of QTP scripts.

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Related articles:

• QTP Recovery Scenario VIDEO
• How to read XML file from QTP
• QTP - How to get number of pages in PDF file?
• QTP Descriptive Programming - operations
• All QTP visual tutorials

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