In the changelog of 17w45b, it said that "Made /execute if <..> return values if used on their own".

I found that the result of the "if blocks" is 1(when source and destination regions match) or 0 (when they do not match).

But this command's "precursor" , /testforblocks , returns the number of matching blocks, not only 0 or 1.

if i want to get 0 or 1, i should use "success" mode. (this mode do not work as intended as well)
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by the way,"if block" could not use on their own.