The ERC20 token standard specifies balanceof() to return a constant.
function balanceOf(address _owner) constant returns (uint256 balance)
But the balance amount might change or am I getting something wrong here?
The constant keyword does not specify what the function returns. A function marked as constant like this one tells you that the function will return a value and will not modify any state variables. A large use for the constant/view keywords is to declare a function that can be called without sending a transaction, i.e. a free "query" of the blockchain.
http://solidity.readthedocs.io/en/develop/contracts.html#view-functions
answered Nov 10 '17 at 13:46
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Why would it be wrong not to use
constantinbalanceof()? The function itself doesn't change any state, it only returnsreturn balances[_owner];– baermathias Nov 10 '17 at 14:00 -
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1What is "constant" is the function, which in Solidity refers to a function that doesn't modify the state of the blockchain, just reads values. Not to be confused with a constant variable, whose value can't be changed once declared. – pabloruiz55 Nov 10 '17 at 23:09
constant on functions is an alias to view, so when executed you can view the contents that function returns
