Where can I see the output of Solidity's sha3 function?

Question

I have written the below code and it runs perfectly. After mining and passing the values along with certain gas value, i get transaction hash as output on the geth console. Now i want to know the output of sha3 function applied in the code?

contract C { 
string a;
string b;
bytes32 d;

function identify(string sm, string bm, bytes32 i) returns (bytes32 hash){
    a = sm;
    b =bm;
    d = i;
    return sha3(sm, bm, i);
}

}

Once mining is done. i type the following command:

c.identify("Bob","Alice",1234);

I get the transaction has i.e

Contract mined! address: 0x1df37eeccc9278b04497b4a3c97388cac3a98e6f    
transactionH
ash: 0x7bf49540c9db92cab84b483514ffebdb600d39889ef2319904bc788d7c87afd9
c.identify("rahul","ankesh",1234,{from:primary,gas:300000})
"0x24d344a11f9aa84d43ccf0e17e635750e3d44fee0c4eaba1c1dea8ebbdaf3376".

Now, where is the output of the sha3 function?

Answer 1

Some options, explicitly label the function constant:

function identify(string sm, string bm, bytes32 i) constant returns (bytes32 hash)

or explicitly perform a call:

c.identify.call("Bob","Alice",1234);

I tested in browser-solidity and you should see the value 0xc479d062d8322fb8b4207d9967174220d6d86d90fef3b5c6cefc8ec6577e21c8.

More info: What is the difference between a transaction and a call?

Answer 2

The return value of a contract call is ignored unless the call is from another contract. The yellow paper has the following sentences:

Aside from evaluating to a new state and transaction substate, message calls also have an extra component---the output data denoted by the byte array $\mathbf{o}$. This is ignored when executing transactions, however message calls can be initiated due to VM-code execution and in this case this information is used.

If you record an event in Solidity, the event logs are visible in the transaction receipt.