11.3.4. Subscripting a map

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The map and unordered_map containers provide the subscript operator and a corresponding at function (§ 9.3.2, p. 348), which are described in Table 11.6 (overleaf). The set types do not support subscripting because there is no “value” associated with a key in a set. The elements are themselves keys, so the operation of “fetching the value associated with a key” is meaningless. We cannot subscript a multimap or an unordered_multimap because there may be more than one value associated with a given key.

Table 11.6. Subscript Operation for map and unordered_map

Like the other subscript operators we’ve used, the map subscript ...

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