I'm running into a problem with solidity with structures containing arrays, can you help me see what I'm missing?Any help would be greatly appreciated!

 struct Info {
    uint a;
    uint256 b;
    uint[] data;

mapping(address => Info) infos;

function set() public {
    infos[msg.sender].a = 1;
    infos[msg.sender].b = 2;

function get() public {
      infos[msg.sender].a; //yes It is equal to 1
      infos[msg.sender].b; //yes It is equal to 2
      infos[msg.sender].data[0]; //The problem here is that anyone calling this function can read data[0]=3
  • My problem is that when someone calls set() and anyone else calls get(), data[0] returns 3, which is weird
    – zmy
    Nov 2, 2021 at 10:52

1 Answer 1


So this works as you said. you pushed value 3 to the array and it returns value 3 at 0 index of the array. if you want data array has 3 elements you should push 3 times a value maybe 0.

  • Maybe my demo gave you the wrong idea, but I already know where I went wrong. View-decorated functions should not use msg.sender, it is empty address!
    – zmy
    Nov 3, 2021 at 8:39

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