The original question below seems to work as expected. The issue happens with the call return data is empty. When the response is nothing, the code below fails.

The following works, but is there a better way to do it?

bytes[] memory val;
for(uint i = 0; i < item.length; i++) {
    (, bytes memory response) = addr.call.value(_value[i])(_data);
    if (response.length != 0) {
        val[i] = response;

I am unable to figure out how to store an array of bytes. I understand that bytes is an array of byte1s, but I want to be able to store multiple bytes in an array? So ideally, I would be able to define bytes[], where each member of that array is a new bytes.

Some example code (which is not working) is:

bytes[] memory val;
for(uint i = 0; i < _value.length; i++) {
    (, bytes memory response) = addr.call.value(_value[i])(_data);
    val[i] = response;

This is reverting on val[i] = response;. Does anyone know why?

  • Don't you feel that there's something a bit odd (to say the least) with val[i] = response? The LHS and RHS are not even of the same type (let alone the fact that you're trying to set each entry in the output array to be equal to the input array). Oct 24, 2019 at 4:09
  • I am adding a quick update and would love your opinion. Oct 24, 2019 at 4:14
  • Also, it looks like you should be using _value.length, not item.length (what are these two variables anyway?). Oct 24, 2019 at 4:14
  • "reverting" or "not compiling"? Oct 24, 2019 at 4:15
  • If "reverting", then please share your execution (or testing) code. What transaction were you trying to execute? Also, there are several undefined symbols in your code, please provide a minimal working example. Oct 24, 2019 at 4:17

1 Answer 1


You should by the least add another internal for loop in your code.

Something like this:

bytes[] memory val = new bytes[](_value.length);
for (uint i = 0; i < _value.length; i++) {
    (bool success, bytes memory response) = addr.call.value(_value[i])(_data);
    require(success, "call failed");
    val[i] = new bytes(response.length);
    for (uint j = 0; j < response.length; j++) {
        val[i][j] = response[j];

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