st: destringing a variable?

["Ms. Marilyn Ibarra" <ibarra@uga.edu>]

I need to destring a variable 'foreign_id' so I can declare a dataset to be panel as follows:

xtset foreign_id year, yearly

However, my variable 'foreign_id' is constructed as follows:

firm      foreign_id
1           5011x
1           5011x
1           5011x
2           0017 
2           0017 
2           0017 
etc.

I guess the solution is to get rid of the 'x' part.  Anyone know how I can easily do this so I am left with: 


firm      foreign_id
1           5011
1           5011
1           5011
2           0017
2           0017 
2           0017 


Thanks,
Marilyn. 
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