InfoPath Dev

 Anyone,

    I have a receipt table and users  may add them using repeatable table.

No      Amount    Reason     Balance 
1         10            Cash           400
2         10            Books         390
3         10            Transport    380
4         10            Cash           370

 -----------------------------------------------

No      Amount    Reason     Balance 
1         10            Cash           400
2         12            Books         388
3         10            Transport    380
4         10            Cash           370 

The Balance will get calculated based on the amount entered.
My issue is how do I loop thru the table when I update line no 2 so it will recalculate all the values.

Using code you can loop from top to bottom and the actions will recalculate. But I am using a browser based form so NO Code eh!.
All I wanna do is to loop using XPath or something with fomula rules where I can touch all the amount on every rows and the balance gets recalculated.

Please someone 

Thank You 

 You actually don't need to loop, you just need to set the default value for the Balance field to be equal to the previous row's Balance field minus the Amount field.  Start with the following formula:

• Balance - Amount 

Then select the Edit xPath (advanced) checkbox, which will change what you see to something like this:

• . - ../my:Amount

Now you need to modify this formula so it looks like the following: 

•  ../preceding-sibling::my:RepeatingTable[1]/my:Balance - ../my:Amount

The preceding-sibling formula will tell InfoPath to get the Balance value from the row immediately preceding the current one.