## Formatting

Forge includes a built-in formatter to enforce consistent code style.

### Format files

Format all Solidity files:

```bash
$ forge fmt
```

Check formatting without making changes:

```bash
$ forge fmt --check
```

This exits with an error if any file needs formatting—useful for CI.

### Configuration

Configure the formatter in `foundry.toml`:

```toml [foundry.toml]
[fmt]
line_length = 120
tab_width = 4
bracket_spacing = true
int_types = "long"
multiline_func_header = "params_first"
quote_style = "double"
number_underscore = "thousands"
single_line_statement_blocks = "preserve"
```

Common options:

| Option | Default | Description |
|--------|---------|-------------|
| `line_length` | 120 | Maximum line length |
| `tab_width` | 4 | Spaces per indentation level |
| `bracket_spacing` | false | Space inside brackets: `{ x }` vs `{x}` |
| `int_types` | "long" | `uint256` vs `uint` |
| `quote_style` | "double" | `"string"` vs `'string'` |
| `number_underscore` | "preserve" | `1_000_000` vs `1000000` |

See the [formatter reference](/config/reference/formatter) for all options.

### Ignoring files

Exclude files from formatting:

```toml [foundry.toml]
[fmt]
ignore = ["src/legacy/**"]
```

### Pre-commit integration

Add formatting checks to git pre-commit hooks:

```bash [.git/hooks/pre-commit]
#!/bin/sh
forge fmt --check
```

Or use a tool like `lefthook` or `husky` for more complex workflows.

### CI integration

Check formatting in CI:

```yaml
- name: Check formatting
  run: forge fmt --check
```