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| -rw-r--r-- | docs/frequently-asked-questions.rst | 17 |
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diff --git a/docs/frequently-asked-questions.rst b/docs/frequently-asked-questions.rst index f960a0d6..9e59e010 100644 --- a/docs/frequently-asked-questions.rst +++ b/docs/frequently-asked-questions.rst @@ -172,6 +172,23 @@ Are mappings iterable? Mappings themselves are not iterable, but you can use a higher-level datastructure on top of it, for example the `iterable mapping <https://github.com/ethereum/dapp-bin/blob/master/library/iterable_mapping.sol>`_. +Can I put arrays inside of a mapping? How do I make a mapping of a mapping? +=========================================================================== + +Mappings are already syntactically similar to arrays as they are, therefore it doesn't make much sense to store an array in them. Rather what you should do is create a mapping of a mapping. + +An example of this would be:: + contract c { + struct myStruct { + uint someNumber; + string someString; + } + mapping(uint => mapping(string => myStruct)) myDynamicMapping; + function storeInMapping() { + myDynamicMapping[1]["Foo"] = myStruct(2, "Bar"); + } + } + Can you return an array or a string from a solidity function call? ================================================================== |