From 0c5156ca50f23b4fe8efb08fc8993e65a3126ae4 Mon Sep 17 00:00:00 2001 From: RJ Date: Tue, 29 Mar 2016 13:05:42 -0500 Subject: [PATCH] Update frequently-asked-questions.rst --- docs/frequently-asked-questions.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/docs/frequently-asked-questions.rst b/docs/frequently-asked-questions.rst index f960a0d6e..9e59e010d 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 `_. +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? ==================================================================