> ## Documentation Index
> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# CODESIZE (0x38)

> Get size of executing code in bytes

<Warning>
  **This page is a placeholder.** All examples on this page are currently AI-generated and are not correct. This documentation will be completed in the future with accurate, tested examples.
</Warning>

## Overview

**Opcode:** `0x38`
**Introduced:** Frontier (EVM genesis)

CODESIZE pushes the byte length of the currently executing code onto the stack.

## Specification

**Stack Input:**

```
[]
```

**Stack Output:**

```
size (uint256, in bytes)
```

**Gas Cost:** 2 (GasQuickStep)

**Operation:**

```
stack.push(code.length)
```

## Behavior

Returns the size of the currently executing bytecode, including deployed code and constructor code.

## Examples

### Basic Usage

```solidity theme={null}
function getCodeSize() public pure returns (uint256 size) {
    assembly {
        size := codesize()
    }
}
```

### Code Copying

```solidity theme={null}
function copyOwnCode() public pure returns (bytes memory code) {
    assembly {
        let size := codesize()
        code := mload(0x40) // Free memory pointer
        mstore(code, size)
        codecopy(add(code, 0x20), 0, size)
        mstore(0x40, add(add(code, 0x20), size))
    }
}
```

## Gas Cost

**Cost:** 2 gas (GasQuickStep)

## Common Usage

### Constructor Detection

During contract construction, CODESIZE includes constructor code. After deployment, only runtime code.

## Implementation

<Tabs>
  <Tab title="TypeScript">
    ```typescript theme={null}
    export function codesize(frame: FrameType): EvmError | null {
      const gasErr = consumeGas(frame, 2n);
      if (gasErr) return gasErr;

      const pushErr = pushStack(frame, BigInt(frame.bytecode.length));
      if (pushErr) return pushErr;

      frame.pc += 1;
      return null;
    }
    ```
  </Tab>
</Tabs>

## References

* [Yellow Paper](https://ethereum.github.io/yellowpaper/paper.pdf) - Section 9.1
* [EVM Codes - CODESIZE](https://www.evm.codes/#38)