# 5.10.0:

$ perl -lwe 'print 0 + "inf"'
inf

$ perl -lwe 'print 0 + unpack "F", pack "H*", "000000000000f07f"'
inf

# 5.8.4:

$ perl -lwe 'print 0 + "inf"'
0

$ perl -lwe 'print 0 + unpack "F", pack "H*", "000000000000f07f"'
inf