Solidity String Conversion – How to Convert a String to Bytes32

bytes32soliditystring

How can I convert a string to a bytes32? Does anyone has a magic function or library which does it?

For example: This works since as input I gave 32-bits. But it won't work with "> 32-bit" chars.

set_txn_hash = a.transact().set("QmVoGzRDscx61k3RHHkLYaMFtxYZi3ps");#32-bit char

–

function get() returns (stringc value){  
    return list.get_head_data();   
}

But if I need to give more character for example contains 48-bit string this won't work. [Q] How could I make this work?

Best Answer

This has worked for me so far. Not sure if it's the best way.

function stringToBytes32(string memory source) public pure returns (bytes32 result) {
    bytes memory tempEmptyStringTest = bytes(source);
    if (tempEmptyStringTest.length == 0) {
        return 0x0;
    }

    assembly {
        result := mload(add(source, 32))
    }
}

Also, remember that strings in solidity are UTF8 so after converting them to bytes each byte is not necessarily a character.

EDIT: shorter version, should work the same.

Related Solutions

Solidity String Conversion – How to Convert a Bytes32 to String

Based on the latest compiler version 0.4.24, I use the following.

function convertingToString()public returns(string){
bytes32 memory hw = "Hello World";
string memory converted = string(hw);
return converted;
}

Using explicit conversion to carry it out. The reverse is also possible.

For versions 0.5.0+ please use (tested from 0.5 to 0.7.2 - it is likely that it will continue to work past 0.7.2):

function bytes32ToString(bytes32 _bytes32) public pure returns (string memory) {
        uint8 i = 0;
        while(i < 32 && _bytes32[i] != 0) {
            i++;
        }
        bytes memory bytesArray = new bytes(i);
        for (i = 0; i < 32 && _bytes32[i] != 0; i++) {
            bytesArray[i] = _bytes32[i];
        }
        return string(bytesArray);
    }

[Ethereum] Solidity return string not hex

Use web3.js like contractInstance.getItem.call(key).

Or mark getItem as constant: function getItem(address key) constant returns (string) and then you can use:

contractInstance.getItem(key)

web3.js will automatically decode the bytes for you. Contracts only have binary data, hex is a more compact way of viewing that data, and that's why you see hex. The binary data is also encoded according to an ABI, so that values can be distinguished, for example between what's just a number and a string.

Best Answer

Related Solutions

Solidity String Conversion – How to Convert a Bytes32 to String

[Ethereum] Solidity return string not hex

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