why is it numeric(0)?

hello,everyone. I have one question:

example 1

x=numeric(0)
y=5
print(x+y)

numeric(0)

example 2

x=numeric(1)
y=5
print(x+y)

[1] 5

why the print(x+y)  is numeric(0) at the first example, but the result is 0
at the second example?

numeric(0) is a zero-length vector of floating point numbers, so your 
first example takes no floating point numbers and adds 5 to each one. The 
result is still no floating point numbers.

numeric(1) is a vector containing a single 0, so the second example takes 
0 and adds 5, to give a vector containing a single 5.


 	-thomas