I know I can return dynamic byte arrays in Solidity, such as in the following code:

function createMemoryArray(uint size) returns (bytes) {
    // Dynamic memory arrays are created using `new`:
    uint[2][] memory arrayOfPairs = new uint[2][](size);
    // Create a dynamic byte array:
    bytes memory b = new bytes(200);
    for (uint i = 0; i < b.length; i++)
        b[i] = byte(i);
    return b;

But is there a way to return something like a dynamic array of strings? I feel like this is just an implementation detail in Solidity, but it would be great if it just serialized everything nicely for me.


Is it possible to return an array of strings ( string[] ) from a Solidity function?

Not yet, as this requires two levels of dynamic arrays (string is a dynamic array itself). Doc

However you can return an Array of Bytes32 ( fixed size of 32 byte) So you can try to do something like this ( you can copy paste on Remix to test it )

pragma solidity ^0.4.11;
contract ArrayOfBytes32 {
    address creator;
    bytes32[10] bytesArray; // size must be fixed

    function ArrayRR() 
        creator = msg.sender;
        uint8 x = 0;
        while(x < bytesArray.length)
            bytesArray[x] = "myString"; 

    function getArray() constant returns (bytes32[10])
        return bytesArray;

    function getValue(uint8 x) constant returns (bytes32)
        return bytesArray[x];

Note that you will have to use web3.toAcsii() doc to convert the result if you use web3 to interact with your contract

  • 1
    Huh, I never would've thought to check the doc FAQs. Nice find and interesting solution! – user9402 Jun 6 '17 at 13:35
  • 1
    Why I can't return a dynamic array of of bytes32 (bytes32[])? – Robert Zaremba Aug 21 '17 at 14:41
  • 2
    You can return a dynamic array of of bytes32 (bytes32[]). What you can't is returning an object which combines two levels of dynamic arrays. – Robert Zaremba Aug 21 '17 at 18:02
  • @RobertZaremba But isn't bytes32 an array itself? Then bytes 32[] is a two dimensional array – Andrey Mar 21 '18 at 14:16
  • 1
    @Andrey Problem is with two levels of dynamic arrays, not a two dimensional arrays. You could have function return two dimensional array of 10 uints each without problem - but you cannot have two dimensional array where both arrays are dynamic. Type "bytes32" just indicate that it allocates 32 bytes in the memory, so it is not dynamic variable - you always know that it will take 32 bytes of memory, therefore it is static variable (cannot change size during runtime). That's why it works :) – Oliver Rydzi Dec 10 '18 at 17:38

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