This is the function. I am very new to this. Can someone please tell me what is wrong in this.

function getData(string Key) constant returns (string[], string[]) {

    uint length = data.length;

    string[] memory key = new string[](length);
    string[] memory hash = new string[](length);

    for(uint i=0; i < data.length; i++ ) {
        Data memory currentData;
        currentData = data[i];

        key[i] = currentData.key;
        hash[i] = currentData.hash;

    return (key,hash);
  • Can you update the question with the complete code? What's data in this function is not defined.
    – Sanchit
    Jul 5 '17 at 4:31

It's complaining about returns(string[]).

You're trying to return variable length arrays but the interface is limited to 16 fixed length arguments or 8 strings, with a further caveat about strings - they can't be passed between contracts.

These are limitations of the current compiler.

This code replicates the same error:

pragma solidity ^0.4.6;

contract TestContract{

    function test() constant returns(string[], string[]) {
        // ^ no good


If you need a workaround for large arrays, you can call return vals by row number. Something like:

function x(uint row) constant returns(string) {
  return myString[row][

Or even:

string[] public myString; 

By declaring it public, you get a "free" getter function that does the same thing. For completeness, I should say that public has additional implications if any contracts inherit the code.

Hope it helps.

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