19

In Solidity, how can I convert the sender address to a string?

The comments in How to convert an address to bytes in Solidity? did not provide a working solution

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  • function toString(address x) internal pure returns (string) { bytes memory b = new bytes(20); for (uint i = 0; i < 20; i++) b[i] = byte(uint8(uint(x) / (2**(8*(19 - i))))); return string(b); } Use internal pure keyword, otherwise you will get a warning. For more information about pure function. – Kushan Gunasekera Jun 18 '18 at 11:12
26

Use abi.encodePacked(x)

where x is the address. (Thanks @k06a)

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  • It works, but the result is not a human-readable string. For a human-readable string, see toAsciiString example in the other answer. – rustyx Apr 9 '18 at 13:22
11

I was not able to read the ABI-encoded string with web3.js. Therefore I added some conversion to the ascii-characters:

function toAsciiString(address x) returns (string) {
    bytes memory s = new bytes(40);
    for (uint i = 0; i < 20; i++) {
        byte b = byte(uint8(uint(x) / (2**(8*(19 - i)))));
        byte hi = byte(uint8(b) / 16);
        byte lo = byte(uint8(b) - 16 * uint8(hi));
        s[2*i] = char(hi);
        s[2*i+1] = char(lo);            
    }
    return string(s);
}

function char(byte b) returns (byte c) {
    if (uint8(b) < 10) return byte(uint8(b) + 0x30);
    else return byte(uint8(b) + 0x57);
}
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  • 1
    There was a problem with the function char(byte b). "TypeError: Operator < not compatible with types bytes1 and int_const 10" I suppose this comparison does work anyway since you probably meant if b is a number then add 0x30 to it. But how do you know if a byte is less than 10 or not anyways? – Billie Jan 16 '19 at 12:25
  • if (b < 10) has to be changed to if (uint8(b) < 10), then the Operator < not compatible with types bytes1 ... error is fixed. I made an edit to the answer. Hope it gets approved. – Jack O'neill Sep 5 '19 at 13:35
  • Thanks for the answer - so far this works in v0.5.10 – pizzarob Sep 5 '19 at 15:04
5

This is method to convert address to hex string:

function toString(address account) public pure returns(string memory) {
    return toString(abi.encodePacked(account));
}

function toString(uint256 value) public pure returns(string memory) {
    return toString(abi.encodePacked(value));
}

function toString(bytes32 value) public pure returns(string memory) {
    return toString(abi.encodePacked(value));
}

function toString(bytes memory data) public pure returns(string memory) {
    bytes memory alphabet = "0123456789abcdef";

    bytes memory str = new bytes(2 + data.length * 2);
    str[0] = '0';
    str[1] = 'x';
    for (uint i = 0; i < data.length; i++) {
        str[2+i*2] = alphabet[uint(uint8(data[i] >> 4))];
        str[3+i*2] = alphabet[uint(uint8(data[i] & 0x0f))];
    }
    return string(str);
}
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