[Ethereum] Integer to hexadecimal number

The Fixed Point Numbers documentation has a warning which says:

Fixed point numbers are not fully supported by Solidity yet. They can be declared, but cannot be assigned to or from.

The warning at the bottom of Rational and Integer Literals says:

Division on integer literals used to truncate in earlier versions, but it will now convert into a rational number, i.e. 5 / 2 is not equal to 2, but to 2.5

Transactions are always executed in the block being mined. So, at any time, block.number will return the block height in which the transaction is being mined.

However, the hash of the block is not known until it is mined, and the output of transactions is part of the hash calculation, so the transaction has no access to the hash of the block being mined.

If this is any consolation, you can get the hash of the latest mined block, i.e. the one right before this block being mined with block.blockhash(block.number - 1).

Try this:

contract Test {
    uint public blockNumber;
    bytes32 public blockHashNow;
    bytes32 public blockHashPrevious;

    function setValues() {
        blockNumber = block.number;
        blockHashNow = block.blockhash(blockNumber);
        blockHashPrevious = block.blockhash(blockNumber - 1);
    }    
}

Make a transaction to setValues() then you will see that:

• blockNumber is set at that number it was mined in
• blockHashNow is set at 0x
• blockHashPrevious is set at the previous block hash indeed