# Solidity console.log() reference

Description: Reference documentation of Hardhat's Solidity console.log() functionality

Note: This document was authored using MDX

  Source: https://github.com/NomicFoundation/hardhat-website/tree/main/src/content/docs/docs/reference/console-log.mdx

Hardhat allows you to print logging messages and contract variables by calling `console.log()` when running your Solidity code in a simulated network or a Solidity test.

To use it, simply import `hardhat/console.sol` and call it as if it were Node.js' [`console.log`](https://nodejs.org/api/console.html#consolelogdata-args). It implements the same formatting options, which in turn uses [`util.format`](https://nodejs.org/api/util.html#utilformatformat-args).

For example, this contract prints a formatted string when it's deployed:

```solidity
// contracts/ConsoleLogExample.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;

import "hardhat/console.sol";

contract ConsoleLogExample {
  constructor() {
    console.log(
      "msg.sender is %s and block number is %d",
      msg.sender,
      block.number
    );
  }
}
```

## Supported functions

You can use `console.log` in any Solidity function, including `view` and `pure`.

## Supported `console.log` overloads

You can call `console.log` with up to 4 parameters in any order of the following types:

- `uint256`
- `string`
- `bool`
- `address`

There are also single parameter functions for the types above, and additionally `bytes`, `bytes1`... up to `bytes32`:

- `console.logInt(int i)`
- `console.logUint(uint i)`
- `console.logString(string memory s)`
- `console.logBool(bool b)`
- `console.logAddress(address a)`
- `console.logBytes(bytes memory b)`
- `console.logBytes1(bytes1 b)`
- `console.logBytes2(bytes2 b)`
- ...
- `console.logBytes32(bytes32 b)`

To check the most up-to-date version, refer to `hardhat/console.sol` in the version you have installed.

## `console.log` in other tools and networks

If you accidentally deploy a contract with a `console.log` or use it in a tool that doesn't support it, it won't have any side effects when run, except for an increased gas cost.

This is because `console.log` works by sending static calls to a well-known contract address that has no code. At runtime, Hardhat detects calls to that address, decodes their input data, and writes it to the terminal.