Returns the position in the receiving buffer of a
needle string.
It returns
0 if
needle is the null string or is not found
or if
start is greater than
the length of the receiving buffer. The search is performed using caseless
comparisons.
By default, the search starts at the first
character of the receiving buffer (that is, the value of
start is
1),
and continues to the end of the buffer. You can override this by specifying
start, the point at which the search starts, and
length, the bounding limit for the search.
If specified,
start must be a positive
whole number and
length must be
a non-negative whole number.
