[Ethereum] How to delete an element at a certain index in an array

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Anyone know how to delete an element in a array? Is there any built in method to do that?

If not, does anyone know of how to implement such a method?

Best Answer

Use the delete operator to delete the element:

delete array[index];

If you don't want to leave a gap, you need to move each element manually:

contract test{
    uint[] array = [1,2,3,4,5];
    function remove(uint index)  returns(uint[]) {
        if (index >= array.length) return;

        for (uint i = index; i<array.length-1; i++){
            array[i] = array[i+1];
        }
        delete array[array.length-1];
        array.length--;
        return array;
    }
}

If you don't care about the order, you can also just copy the last element into the empty spot, then delete the last element.

Related Solutions

[Ethereum] How to delete array at index

You're getting that problem because you're trying to search through the indexes of the array using an address which is not valid, you must search using uints. You can however use a pattern to make the index of the address easily retrievable.

Here's a pattern I use to do just this

address[]   public sellers;
mapping (address => uint256) public arrayIndexes;
function addAddress(address _addr) public {
    uint id = sellers.length;
    arrayIndexes[_addr] = id;
    sellers.push(_addr);
}

function removeAddress(address _addr) public {
    uint id = arrayIndexes[_addr];
    delete sellers[id];
}

One thing to note is that this doesn't preserve order in the array, and whatever address you delete will turn into the nu;l address 0x0000000000000000000000000000000000000000

Best Answer

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[Ethereum] How to delete array at index

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