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# mqtt_subscribe

Subscribes the client to a topic.

## C Language

int mqtt_subscribe( MQTT handle, const char* topic);

Example | MQTT Vuser Functions

## Arguments

Name | Comments
--- | ---
handle | The MQTT client handle returned by mqtt_create.
topic | The destination topic as a null-terminated string. The topic can contain wildcards. Examples: `myhome/kitchen/temperature/1`, `region2/#` `region2/WeatherStation/+/temperature`

## General Information

mqtt_subscribe subscribes the client to a topic or a set of topics that match the wildcard. The broker sends messages published on these topics automatically.

If the connection is lost during mqtt_subscribe, the client tries to subscribe again after reconnection.

If invalid arguments are passed, the Vuser aborts, even if Continue on error is set.

## Return Values

MQTT_SUCCESS or MQTT_FAIL

## Parameterization

Standard parameterization is available for this function.

## Example

/* Subscribe to the topics matching the wildcard "sensors/temperature/#"*/

`mqtt_subscribe(client, "sensors/temperature/#");`

/* Now the client will receive messages to subscribed topics */

/* Unsubscribe from the topic "sensors/temperature/surface/3" */

`mqtt_unsubscribe(client, "sensors/temperature/surface/3");`

/* Now the client will receive messages from all subscriptions except for "sensors/temperature/surface/3" */

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