Hey is there a way to convert bytes to uint in Solidity?
6
4
You can use this function to convert bytes to unit:
pragma solidity ^0.4.23;
contract mycontract {
function bytesToUint(bytes b) public returns (uint256){
uint256 number;
for(uint i=0;i<b.length;i++){
number = number + uint(b[i])*(2**(8*(b.length-(i+1))));
}
return number;
}
}
The amount of gas used depends on the length of your bytes variable, but this is cheap. Converting a bytes variable of length 20 uses about 420 gas.
Hope this helps
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Getting an error in Remix: TypeError: Return argument type bytes memory is not implicitly convertible to expected type uint256 – arete Jun 14 '18 at 15:02
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Can you show me your code?, this works for me well in remix, I put the whole code so you can just copy and paste it. Let me know – Jaime Jun 14 '18 at 15:13
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Oh there you go. I think your first post had the return value as "b". This works. Thanks! – arete Jun 14 '18 at 15:25
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1
Slicing an uint out of bytes using inline assembly
function sliceUint(bytes bs, uint start)
internal pure
returns (uint)
{
require(bs.length >= start + 32, "slicing out of range");
uint x;
assembly {
x := mload(add(bs, add(0x20, start)))
}
return x;
}
0
The fully working modern solution from Consensys dude can be found here:
https://github.com/GNSPS/solidity-bytes-utils/blob/master/contracts/BytesLib.sol
The accepted answer's code is not compiling in Solidity >0.5; with implicit type conversion error.
bytesvalue and the correspondinguintvalue you would like to see. – user19510 Jun 14 '18 at 14:52