This will not affect your code.
When you call
that is the same as if you had invoked
which is calling imag() on the vector of four characters, 'p', 'a', 'r', 't' .
In many circumstances, characters automatically convert to the numeric codes used to internally encode the characters, such as 112 for 'p', and 97 for 'a' . So imag() treats this as a vector of real-valued double precision numbers. But the imaginary() portion of those is all 0 so 0 0 0 0 gets returned.