Re: need for operator[] in map
<subramanian100in@yahoo.com> wrote:
For inserting new elements in map, we can use insert member function.
To know if an element exists or not in a map, we can use count or find
member function.
Also, we can use the iterator returned by find to modify the mapped
value of an existing key.
When we use operator[], it may add an element into the map if the key
already doesn't exist, which may not be always wanted.
Given this, I am unable to understand the reason as to why we have
operator[] in map whose functionality can be achieved by other member
functions.
Kindly clarify.
For the answer, you will have to ask the standards body, or at least
Alex Stepanov (the creator of the STL.)
For now, maybe the explanation from SGI's website will do?
Note that the definition of operator[] is extremely simple: m[k] is
equivalent to (*((m.insert(value_type(k,
data_type()))).first)).second. Strictly speaking, this member
function is unnecessary: it exists only for convenience.
(http://www.sgi.com/tech/stl/Map.html)
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