Short circuit operators always evaluate in boolean context. In boolean context there are only true and false. The string "0" and numberic 0 are, among others, false. But, 0 (or empty string) is defined. So you need to check for defined-ness to allow them. See True or False? A Quick Reference Guide.
in reply to Re^2: How to assign string "0" in short circuit
in thread How to assign string "0" in short circuit
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