Custom format cell to consider dash as zero in excel

[adpatel]

I import data from web external query in excel in which zero value represented as dash, to further calculation on this I need to consider this dash as zero
for that I have macro to convert dash to zero but, data gets refreshed every 5 min. so I need to run that replacement macro every 5 min.
instead of this I want to do is,apply format cell in which dash will be considered as zero and I will import data by selecting preserve format, so no need to run replacement macro every 5 min.
So pls let me know custom format cell in which positive value ll be consider as positive,negative as negative but dashes as zero
thank you.

 

[Peter_SSs]

A custom format does not change the underlying value in the cell. So if the dash is causing a calculation problem, custom formatting won't help.
Perhaps if you tell us about the "further calculation", that can possibly be modified to treat the dashes as zero without actually changing them.

 

[adpatel]

OK, I got your point.
I am 1st coping this data to another range and then I use the copied data and new refreshed data for comparision

 

[Peter_SSs]

So how do the dashes impact on that comparison?

Perhaps you could show us a small set of dummy sample data that shows 'current' & 'previous' data and how you want them compared?