---
name: "libcurl-url"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/libcurl-url"
---

# libcurl-url(3)

URL interface overview

## NAME

libcurl-url - URL interface overview

## DESCRIPTION

The URL interface provides functions for parsing and generating URLs.

## INCLUDE

You still only include \<curl/curl.h\> in your code.

## CREATE

Create a handle that holds URL info and resources with *[curl\_url(3)](/curl_url/3.md)*:

```
  CURLU *h = curl_url();
```

## CLEANUP

When done with it, clean it up with *[curl\_url\_cleanup(3)](/curl_url_cleanup/3.md)*

```
  curl_url_cleanup(h);
```

## DUPLICATE

When you need a copy of a handle, duplicate it with *[curl\_url\_dup(3)](/curl_url_dup/3.md)*:

```
  CURLU *nh = curl_url_dup(h);
```

## PARSING

By setting a URL to the handle with *[curl\_url\_set(3)](/curl_url_set/3.md)*, the URL is parsed and stored in the handle. If the URL is not syntactically correct it returns an error instead.

```
  rc = curl_url_set(h, CURLUPART_URL,
                    "https://example.com:449/foo/bar?name=moo", 0);
```

The zero in the fourth argument is a bitmask for changing specific features.

If successful, this stores the URL in its individual parts within the handle.

## REDIRECT

When a handle already contains info about a URL, setting a relative URL makes it "redirect" to that.

```
  rc = curl_url_set(h, CURLUPART_URL, "../test?another", 0);
```

## GET URL

The **CURLU** handle represents a URL and you can easily extract that with *[curl\_url\_get(3)](/curl_url_get/3.md)*:

```
  char *url;
  rc = curl_url_get(h, CURLUPART_URL, &url, 0);
  curl_free(url);
```

The zero in the fourth argument is a bitmask for changing specific features.

## GET PARTS

When a URL has been parsed or parts have been set, you can extract those pieces from the handle at any time.

```
  rc = curl_url_get(h, CURLUPART_FRAGMENT, &fragment, 0);
  rc = curl_url_get(h, CURLUPART_HOST, &host, 0);
  rc = curl_url_get(h, CURLUPART_PASSWORD, &password, 0);
  rc = curl_url_get(h, CURLUPART_PATH, &path, 0);
  rc = curl_url_get(h, CURLUPART_PORT, &port, 0);
  rc = curl_url_get(h, CURLUPART_QUERY, &query, 0);
  rc = curl_url_get(h, CURLUPART_SCHEME, &scheme, 0);
  rc = curl_url_get(h, CURLUPART_USER, &user, 0);
  rc = curl_url_get(h, CURLUPART_ZONEID, &zoneid, 0);
```

Extracted parts are not URL decoded unless the user also asks for it with the *CURLU\_URLDECODE* flag set in the fourth bitmask argument.

Remember to free the returned string with *[curl\_free(3)](/curl_free/3.md)* when you are done with it.

## SET PARTS

A user can set individual URL parts, either after having parsed a full URL or instead of parsing one.

```
  rc = curl_url_set(urlp, CURLUPART_FRAGMENT, "anchor", 0);
  rc = curl_url_set(urlp, CURLUPART_HOST, "www.example.com", 0);
  rc = curl_url_set(urlp, CURLUPART_PASSWORD, "doe", 0);
  rc = curl_url_set(urlp, CURLUPART_PATH, "/index.html", 0);
  rc = curl_url_set(urlp, CURLUPART_PORT, "443", 0);
  rc = curl_url_set(urlp, CURLUPART_QUERY, "name=john", 0);
  rc = curl_url_set(urlp, CURLUPART_SCHEME, "https", 0);
  rc = curl_url_set(urlp, CURLUPART_USER, "john", 0);
  rc = curl_url_set(urlp, CURLUPART_ZONEID, "eth0", 0);
```

Set parts are not URL encoded unless the user asks for it with the *CURLU\_URLENCODE* flag.

## CURLU\_APPENDQUERY

An application can append a string to the right end of the query part with the *CURLU\_APPENDQUERY* flag to *[curl\_url\_set(3)](/curl_url_set/3.md)*.

Imagine a handle that holds the URL "https://example.com/?shoes=2". An application can then add the string "hat=1" to the query part like this:

```
  rc = curl_url_set(urlp, CURLUPART_QUERY, "hat=1", CURLU_APPENDQUERY);
```

It notices the lack of an ampersand (&) separator and injects one, and the handle's full URL then equals "https://example.com/?shoes=2&hat=1".

The appended string can of course also get URL encoded on add, and if asked to URL encode, the encoding process skips the '=' character. For example, append "candy=N&N" to what we already have, and URL encode it to deal with the ampersand in the data:

```
  rc = curl_url_set(urlp, CURLUPART_QUERY, "candy=N&N",
                    CURLU_APPENDQUERY | CURLU_URLENCODE);
```

Now the URL looks like

```
  https://example.com/?shoes=2&hat=1&candy=N%26N
```

## NOTES

A URL with a literal IPv6 address can be parsed even when IPv6 support is not enabled.

## SEE ALSO

[**CURLOPT\_URL**(3)](/CURLOPT_URL/3.md), [**curl\_url**(3)](/curl_url/3.md), [**curl\_url\_cleanup**(3)](/curl_url_cleanup/3.md), [**curl\_url\_dup**(3)](/curl_url_dup/3.md), [**curl\_url\_get**(3)](/curl_url_get/3.md), [**curl\_url\_set**(3)](/curl_url_set/3.md), [**curl\_url\_strerror**(3)](/curl_url_strerror/3.md)