diff --git a/solidity/abi_encoding.md b/solidity/abi_encoding.md new file mode 100644 index 0000000..1894d17 --- /dev/null +++ b/solidity/abi_encoding.md @@ -0,0 +1,24 @@ +## ABI encoding + +* the solidity built-in function `abi.encode` encodes solidity types into raw bytes, that can be interpreted directly by the EVM. + + +``` +contract StringEncoding { + bytes public encodedString = abi.encode("hacking"); +} +``` + +* this is what happens: + 1. 1st (32 bytes) word = offset → indicates at which bytes index the string starts. If you count 32 from the beginning (= index 32), you will reach the starting point of where the actual encoded string starts. + 2. 2nd (32 bytes) word = string length → in the case of the string, this indicates how many characters (including whitespaces) are included in the string. + 3. 3rd (32 bytes) word = the actual utf8 encoded string → each individual bytes corresponds to hex notation of a letter / character encoded in utf8. + +
+ +#### other ABI Encodings + +* address payable -> address +* contract -> address +* enum -> uint8 +* struct -> tuple of elementry types