> For the complete documentation index, see [llms.txt](https://thryec.gitbook.io/dev-compedium/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://thryec.gitbook.io/dev-compedium/ethereum/yul/memory/arrays.md).

# Arrays

#### Fixed Length Arrays

* Under the hood, will behave like structs

```solidity
function fixedArray() external {
        bytes32 x40;
        assembly {
            x40 := mload(0x40)
        }
        emit MemoryPointer(x40); // 0x80 
        uint256[2] memory arr = [uint256(5), uint256(6)];
        assembly {
            x40 := mload(0x40)
        }
        emit MemoryPointer(x40); // 0xc0
    } 
// 0xc0 - 0x80 = 64 bytes 
```

#### Dynamic Length Arrays

* To access a dynamic array, we have to add 32 bytes (or 0x20) to the memory location to skip the location that stores length of the array, and read the first item

```solidity
function args(uint256[] memory arr) external {
        bytes32 location;
        bytes32 len;
        bytes32 valueAtIndex0;
        bytes32 valueAtIndex1;
        assembly {
            location := arr
            len := mload(arr)
            valueAtIndex0 := mload(add(arr, 0x20))
            valueAtIndex1 := mload(add(arr, 0x40))
            // ...
        }
        emit Debug(location, len, valueAtIndex0, valueAtIndex1);
    }
// if array = [4, 5]: 
// location: 0x80
// length: 0x2 
// valueAtIndex0 = 0x4
// valueAtIndex1 = 0x5 
```

#### Gotchas