# Getting started

HTML: [altophp.com/code-diff/getting-started](https://altophp.com/code-diff/getting-started/)

Compare two strings, then choose a renderer for the destination of the result.

```php
<?php

require __DIR__.'/vendor/autoload.php';

use Alto\Code\Diff\Diff;
use Alto\Code\Diff\Renderer\UnifiedRenderer;

$old = "line one\nline two\n";
$new = "line one\nline two changed\n";

$result = Diff::build()->compare($old, $new);

echo (new UnifiedRenderer('old.txt', 'new.txt'))->render($result);
```

The output is a standard unified diff:

```diff
--- old.txt
+++ new.txt
@@ -1,2 +1,2 @@
 line one
-line two
+line two changed
```

The returned string has no final line break. Append `PHP_EOL` when the output
destination requires one. Source newline-at-EOF metadata remains available in
the diff result.

`Diff::build()` creates an immutable builder. Each configuration method returns a new instance, so a configured builder can be reused safely.

Next, configure [diffing](https://altophp.com/code-diff/diffing.md), select another [renderer](https://altophp.com/code-diff/rendering.md),
exchange unified [formats](https://altophp.com/code-diff/formats.md), or handle [errors](https://altophp.com/code-diff/errors.md).

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Previous: [Installation](https://altophp.com/code-diff/installation.md)
Next: [Diffing](https://altophp.com/code-diff/diffing.md)

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ALTO\CODE DIFF: [altophp.com/code-diff](https://altophp.com/code-diff/)
ALTO(PHP): [altophp.com](https://altophp.com/)