---
name: "xcb_get_property"
section: "3"
platform: "linux"
package: "libxcb"
version: "1.17.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/xcb_get_property"
---

# xcb\_get\_property(3)

Gets a window property

## NAME

xcb\_get\_property - Gets a window property

## SYNOPSIS

**#include \<xcb/xproto.h\>**

### Request function

xcb\_get\_property\_cookie\_t **xcb\_get\_property**(xcb\_connection\_t \**conn*, uint8\_t *\_delete*, xcb\_window\_t *window*, xcb\_atom\_t *property*, xcb\_atom\_t *type*, uint32\_t *long\_offset*, uint32\_t *long\_length*);

### Reply datastructure

```

typedef struct xcb_get_property_reply_t {
    uint8_t    response_type;
    uint8_t    format;
    uint16_t   sequence;
    uint32_t   length;
    xcb_atom_t type;
    uint32_t   bytes_after;
    uint32_t   value_len;
    uint8_t    pad0[12];
} xcb_get_property_reply_t;
```

### Reply function

xcb\_get\_property\_reply\_t \***xcb\_get\_property\_reply**(xcb\_connection\_t \**conn*, xcb\_get\_property\_cookie\_t *cookie*, xcb\_generic\_error\_t \*\**e*);

### Reply accessors

void \***xcb\_get\_property\_value**(const xcb\_get\_property\_request\_t \**reply*);

int **xcb\_get\_property\_value\_length**(const xcb\_get\_property\_reply\_t \**reply*);

xcb\_generic\_iterator\_t **xcb\_get\_property\_value\_end**(const xcb\_get\_property\_reply\_t \**reply*);\

## REQUEST ARGUMENTS

- *conn*

  The XCB connection to X11.

- *\_delete*

  Whether the property should actually be deleted. For deleting a property, the specified *type* has to match the actual property type.

- *window*

  The window whose property you want to get.

- *property*

  The property you want to get (an atom).

- *type*

  The type of the property you want to get (an atom).

- *long\_offset*

  Specifies the offset (in 32-bit multiples) in the specified property where the data is to be retrieved.

- *long\_length*

  Specifies how many 32-bit multiples of data should be retrieved (e.g. if you set *long\_length* to 4, you will receive 16 bytes of data).

## REPLY FIELDS

- *response\_type*

  The type of this reply, in this case *XCB\_GET\_PROPERTY*. This field is also present in the *xcb\_generic\_reply\_t* and can be used to tell replies apart from each other.

- *sequence*

  The sequence number of the last request processed by the X11 server.

- *length*

  The length of the reply, in words (a word is 4 bytes).

- *format*

  Specifies whether the data should be viewed as a list of 8-bit, 16-bit, or 32-bit quantities. Possible values are 8, 16, and 32. This information allows the X server to correctly perform byte-swap operations as necessary.

- *type*

  The actual type of the property (an atom).

- *bytes\_after*

  The number of bytes remaining to be read in the property if a partial read was performed.

- *value\_len*

  The length of value. You should use the corresponding accessor instead of this field.

## DESCRIPTION

Gets the specified *property* from the specified *window*. Properties are for example the window title (*WM\_NAME*) or its minimum size (*WM\_NORMAL\_HINTS*). Protocols such as EWMH also use properties - for example EWMH defines the window title, encoded as UTF-8 string, in the *\_NET\_WM\_NAME* property.

TODO: talk about *type*

TODO: talk about *delete*

TODO: talk about the offset/length thing. what's a valid use case?

## RETURN VALUE

Returns an *xcb\_get\_property\_cookie\_t*. Errors have to be handled when calling the reply function *xcb\_get\_property\_reply*.

If you want to handle errors in the event loop instead, use *xcb\_get\_property\_unchecked*. See **[xcb-requests(3)](/xcb-requests/3.md)** for details.

## ERRORS

- *xcb\_atom\_error\_t*

  *property* or *type* do not refer to a valid atom.

- *xcb\_value\_error\_t*

  The specified *long\_offset* is beyond the actual property length (e.g. the property has a length of 3 bytes and you are setting *long\_offset* to 1, resulting in a byte offset of 4).

- *xcb\_window\_error\_t*

  The specified *window* does not exist.

## EXAMPLE

```

/*
 * Prints the WM_NAME property of the window.
 *
 */
void my_example(xcb_connection_t *c, xcb_window_t window) {
    xcb_get_property_cookie_t cookie;
    xcb_get_property_reply_t *reply;
    /* These atoms are predefined in the X11 protocol. */
    xcb_atom_t property = XCB_ATOM_WM_NAME;
    xcb_atom_t type = XCB_ATOM_STRING;
    // TODO: a reasonable long_length for WM_NAME?
    cookie = xcb_get_property(c, 0, window, property, type, 0, 0);
    if ((reply = xcb_get_property_reply(c, cookie, NULL))) {
        int len = xcb_get_property_value_length(reply);
        if (len == 0) {
            printf("TODO\n");
            free(reply);
            return;
        }
        printf("WM_NAME is %.*s\n", len,
               (char*)xcb_get_property_value(reply));
    }
    free(reply);
}
```

## SEE ALSO

[**xcb-requests**(3)](/xcb-requests/3.md), [**xcb-examples**(3)](/xcb-examples/3.md), [**xcb\_intern\_atom**(3)](/xcb_intern_atom/3.md), [**xprop**(1)](/xprop/1.md)

## AUTHOR

Generated from xproto.xml. Contact xcb@lists.freedesktop.org for corrections and improvements.