# Amazon SQS code examples using the AWS SDK for C\$1\$1
<a name="examples-sqs"></a>

Amazon Simple Queue Service (Amazon SQS) is a fully managed message queuing service that makes it easy to decouple and scale microservices, distributed systems, and serverless applications. You can use the following examples to program [Amazon SQS](https://aws.amazon.com/sqs) using the AWS SDK for C\$1\$1.

**Note**  
Only the code that is necessary to demonstrate certain techniques is supplied in this Guide, but the [complete example code is available on GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp). On GitHub you can download a single source file or you can clone the repository locally to get, build, and run all examples.

**Topics**
+ [Working with Amazon SQS Message Queues](examples-sqs-message-queues.md)
+ [Sending, Receiving, and Deleting Amazon SQS Messages](examples-sqs-messages.md)
+ [Enabling Long Polling for Amazon SQS Message Queues](examples-sqs-long-polling.md)
+ [Setting Visibility Timeout in Amazon SQS](examples-sqs-visibility-timeout.md)
+ [Using Dead Letter Queues in Amazon SQS](examples-sqs-dead-letter-queues.md)

# Working with Amazon SQS Message Queues
<a name="examples-sqs-message-queues"></a>

A *message queue* is the logical container you use to send messages reliably in Amazon SQS. There are two types of queues: *standard* and *first-in, first-out* (FIFO). To learn more about queues and the differences between these types, see the [Amazon Simple Queue Service Developer Guide](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/).

These C\$1\$1 examples show you how to use the AWS SDK for C\$1\$1 to create, list, delete, and get the URL of an Amazon SQS queue.

## Prerequisites
<a name="codeExamplePrereq"></a>

Before you begin, we recommend you read [Getting started using the AWS SDK for C\$1\$1](getting-started.md). 

Download the example code and build the solution as described in [Getting started on code examples](getting-started-code-examples.md). 

To run the examples, the user profile your code uses to make the requests must have proper permissions in AWS (for the service and the action). For more information, see [Providing AWS credentials](credentials.md).

## Create a Queue
<a name="sqs-create-queue"></a>

Use the SQSClient class `CreateQueue` member function, and provide it with a [CreateQueueRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_create_queue_request.html) object that describes the queue parameters.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/CreateQueueRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::CreateQueueRequest request;
    request.SetQueueName(queueName);

    const Aws::SQS::Model::CreateQueueOutcome outcome = sqsClient.CreateQueue(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully created queue " << queueName << " with a queue URL "
                  << outcome.GetResult().GetQueueUrl() << "." << std::endl;
    }
    else {
        std::cerr << "Error creating queue " << queueName << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/create_queue.cpp).

## List Queues
<a name="sqs-list-queues"></a>

To list Amazon SQS queues for your account, call the SQSClient class `ListQueues` member function, and pass it a [ListQueuesRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_list_queues_request.html) object.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/ListQueuesRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::ListQueuesRequest listQueuesRequest;

    Aws::String nextToken; // Used for pagination.
    Aws::Vector<Aws::String> allQueueUrls;

    do {
        if (!nextToken.empty()) {
            listQueuesRequest.SetNextToken(nextToken);
        }
        const Aws::SQS::Model::ListQueuesOutcome outcome = sqsClient.ListQueues(
                listQueuesRequest);
        if (outcome.IsSuccess()) {
            const Aws::Vector<Aws::String> &queueUrls = outcome.GetResult().GetQueueUrls();
            allQueueUrls.insert(allQueueUrls.end(),
                                queueUrls.begin(),
                                queueUrls.end());

            nextToken = outcome.GetResult().GetNextToken();
        }
        else {
            std::cerr << "Error listing queues: " <<
                      outcome.GetError().GetMessage() << std::endl;
            return false;
        }

    } while (!nextToken.empty());

    std::cout << allQueueUrls.size() << " Amazon SQS queue(s) found." << std::endl;
    for (const auto &iter: allQueueUrls) {
        std::cout << " " << iter << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/list_queues.cpp).

## Get the Queue’s URL
<a name="sqs-get-queue-url"></a>

To get the URL for an existing Amazon SQS queue, call the SQSClient class `GetQueueUrl` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/GetQueueUrlRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::GetQueueUrlRequest request;
    request.SetQueueName(queueName);

    const Aws::SQS::Model::GetQueueUrlOutcome outcome = sqsClient.GetQueueUrl(request);
    if (outcome.IsSuccess()) {
        std::cout << "Queue " << queueName << " has url " <<
                  outcome.GetResult().GetQueueUrl() << std::endl;
    }
    else {
        std::cerr << "Error getting url for queue " << queueName << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/get_queue_url.cpp).

## Delete a Queue
<a name="sqs-delete-queue"></a>

Provide the [URL](#sqs-get-queue-url) to the SQSClient class `DeleteQueue` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/core/client/DefaultRetryStrategy.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/DeleteQueueRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::Model::DeleteQueueRequest request;
    request.SetQueueUrl(queueURL);

    const Aws::SQS::Model::DeleteQueueOutcome outcome = sqsClient.DeleteQueue(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully deleted queue with url " << queueURL <<
                  std::endl;
    }
    else {
        std::cerr << "Error deleting queue " << queueURL << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/delete_queue.cpp).

## More Info
<a name="more-info"></a>
+  [How Amazon SQS Queues Work](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-how-it-works.html) in the Amazon Simple Queue Service Developer Guide
+  [CreateQueue](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_CreateQueue.html) in the Amazon Simple Queue Service API Reference
+  [GetQueueUrl](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_GetQueueUrl.html) in the Amazon Simple Queue Service API Reference
+  [ListQueues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ListQueues.html) in the Amazon Simple Queue Service API Reference
+  [DeleteQueues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_DeleteQueues.html) in the Amazon Simple Queue Service API Reference

# Sending, Receiving, and Deleting Amazon SQS Messages
<a name="examples-sqs-messages"></a>

Messages are always delivered using an [SQS queue](examples-sqs-message-queues.md). These C\$1\$1 examples show you how to use the AWS SDK for C\$1\$1 to send, receive, and delete Amazon SQS messages from SQS queues.

## Prerequisites
<a name="codeExamplePrereq"></a>

Before you begin, we recommend you read [Getting started using the AWS SDK for C\$1\$1](getting-started.md). 

Download the example code and build the solution as described in [Getting started on code examples](getting-started-code-examples.md). 

To run the examples, the user profile your code uses to make the requests must have proper permissions in AWS (for the service and the action). For more information, see [Providing AWS credentials](credentials.md).

## Send a Message
<a name="sqs-message-send"></a>

You can add a single message to an Amazon SQS queue by calling the SQSClient class `SendMessage` member function. You provide `SendMessage` with a [SendMessageRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_send_message_request.html) object containing the queue’s [URL](examples-sqs-message-queues.md#sqs-get-queue-url), the message body, and an optional delay value (in seconds).

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/SendMessageRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::SendMessageRequest request;
    request.SetQueueUrl(queueUrl);
    request.SetMessageBody(messageBody);

    const Aws::SQS::Model::SendMessageOutcome outcome = sqsClient.SendMessage(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully sent message to " << queueUrl <<
                  std::endl;
    }
    else {
        std::cerr << "Error sending message to " << queueUrl << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/send_message.cpp).

## Receive Messages
<a name="sqs-messages-receive"></a>

Retrieve any messages that are currently in the queue by calling the SQSClient class `ReceiveMessage` member function, passing it the queue’s URL. Messages are returned as a list of [Message](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_message.html) objects.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/ReceiveMessageRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::ReceiveMessageRequest request;
    request.SetQueueUrl(queueUrl);
    request.SetMaxNumberOfMessages(1);

    const Aws::SQS::Model::ReceiveMessageOutcome outcome = sqsClient.ReceiveMessage(
            request);
    if (outcome.IsSuccess()) {

        const Aws::Vector<Aws::SQS::Model::Message> &messages =
                outcome.GetResult().GetMessages();
        if (!messages.empty()) {
            const Aws::SQS::Model::Message &message = messages[0];
            std::cout << "Received message:" << std::endl;
            std::cout << "  MessageId: " << message.GetMessageId() << std::endl;
            std::cout << "  ReceiptHandle: " << message.GetReceiptHandle() << std::endl;
            std::cout << "  Body: " << message.GetBody() << std::endl << std::endl;
        }
        else {
            std::cout << "No messages received from queue " << queueUrl <<
                      std::endl;

        }
    }
    else {
        std::cerr << "Error receiving message from queue " << queueUrl << ": "
                  << outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/receive_message.cpp).

### Delete Messages after Receipt
<a name="sqs-messages-delete"></a>

After receiving a message and processing its contents, delete the message from the queue by sending the message’s receipt handle and the queue URL to the SQSClient class `DeleteMessage` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/DeleteMessageRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::Model::DeleteMessageRequest request;
    request.SetQueueUrl(queueUrl);
    request.SetReceiptHandle(messageReceiptHandle);

    const Aws::SQS::Model::DeleteMessageOutcome outcome = sqsClient.DeleteMessage(
            request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully deleted message from queue " << queueUrl
                  << std::endl;
    }
    else {
        std::cerr << "Error deleting message from queue " << queueUrl << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/receive_message.cpp).

## More Info
<a name="more-info"></a>
+  [How Amazon SQS Queues Work](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-how-it-works.html) in the Amazon Simple Queue Service Developer Guide
+  [SendMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessage.html) in the Amazon Simple Queue Service API Reference
+  [SendMessageBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessageBatch.html) in the Amazon Simple Queue Service API Reference
+  [ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html) in the Amazon Simple Queue Service API Reference
+  [DeleteMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_DeleteMessage.html) in the Amazon Simple Queue Service API Reference

# Enabling Long Polling for Amazon SQS Message Queues
<a name="examples-sqs-long-polling"></a>

Amazon SQS uses *short polling* by default, querying only a subset of the servers—based on a weighted random distribution—to determine whether any messages are available for inclusion in the response.

Long polling helps reduce your cost of using Amazon SQS by reducing the number of empty responses when there are no messages available to return in reply to a ReceiveMessage request sent to an Amazon SQS queue and eliminating false empty responses. You can set a long polling frequency from *1–20 seconds*.

## Prerequisites
<a name="codeExamplePrereq"></a>

Before you begin, we recommend you read [Getting started using the AWS SDK for C\$1\$1](getting-started.md). 

Download the example code and build the solution as described in [Getting started on code examples](getting-started-code-examples.md). 

To run the examples, the user profile your code uses to make the requests must have proper permissions in AWS (for the service and the action). For more information, see [Providing AWS credentials](credentials.md).

## Enable Long Polling when Creating a Queue
<a name="sqs-long-polling-create-queue"></a>

To enable long polling when creating an Amazon SQS queue, set the `ReceiveMessageWaitTimeSeconds` attribute on the [CreateQueueRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_create_queue_request.html) object before calling the SQSClient class’ `CreateQueue` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/CreateQueueRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::CreateQueueRequest request;
    request.SetQueueName(queueName);
    request.AddAttributes(
            Aws::SQS::Model::QueueAttributeName::ReceiveMessageWaitTimeSeconds,
            pollTimeSeconds);

    const Aws::SQS::Model::CreateQueueOutcome outcome = sqsClient.CreateQueue(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully created queue " << queueName <<
                  std::endl;
    }
    else {
        std::cout << "Error creating queue " << queueName << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/long_polling_on_create_queue.cpp).

## Enable Long Polling on an Existing Queue
<a name="sqs-long-polling-existing-queue"></a>

In addition to enabling long polling when creating a queue, you can also enable it on an existing queue by setting `ReceiveMessageWaitTimeSeconds` on the [SetQueueAttributesRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_set_queue_attributes_request.html) before calling the SQSClient class’ `SetQueueAttributes` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/SetQueueAttributesRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::SetQueueAttributesRequest request;
    request.SetQueueUrl(queueURL);
    request.AddAttributes(
            Aws::SQS::Model::QueueAttributeName::ReceiveMessageWaitTimeSeconds,
            pollTimeSeconds);

    const Aws::SQS::Model::SetQueueAttributesOutcome outcome = sqsClient.SetQueueAttributes(
            request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully updated long polling time for queue " <<
                  queueURL << " to " << pollTimeSeconds << std::endl;
    }
    else {
        std::cout << "Error updating long polling time for queue " <<
                  queueURL << ": " << outcome.GetError().GetMessage() <<
                  std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/long_polling_on_existing_queue.cpp).

## Enable Long Polling on Message Receipt
<a name="sqs-long-polling-receive-message"></a>

You can enable long polling when receiving a message by setting the wait time in seconds on the [ReceiveMessageRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_receive_message_request.html) that you supply to the SQSClient class’ ReceiveMessage member function.

**Note**  
You should make sure that the AWS client’s request timeout is larger than the maximum long poll time (20s) so that your `ReceiveMessage` requests don’t time out while waiting for the next poll event\$1

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/ReceiveMessageRequest.h>
```

 **Code** 

```
    Aws::SQS::SQSClient sqsClient(customConfiguration);

    Aws::SQS::Model::ReceiveMessageRequest request;
    request.SetQueueUrl(queueUrl);
    request.SetMaxNumberOfMessages(1);
    request.SetWaitTimeSeconds(waitTimeSeconds);

    auto outcome = sqsClient.ReceiveMessage(request);
    if (outcome.IsSuccess()) {
        const auto &messages = outcome.GetResult().GetMessages();
        if (messages.empty()) {
            std::cout << "No messages received from queue " << queueUrl <<
                      std::endl;
        }
        else {
            const auto &message = messages[0];
            std::cout << "Received message:" << std::endl;
            std::cout << "  MessageId: " << message.GetMessageId() << std::endl;
            std::cout << "  ReceiptHandle: " << message.GetReceiptHandle() << std::endl;
            std::cout << "  Body: " << message.GetBody() << std::endl << std::endl;
        }
    }
    else {
        std::cout << "Error receiving message from queue " << queueUrl << ": "
                  << outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/long_polling_on_message_receipt.cpp).

## More Info
<a name="more-info"></a>
+  [Amazon SQS Long Polling](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-long-polling.html) in the Amazon Simple Queue Service Developer Guide
+  [CreateQueue](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_CreateQueue.html) in the Amazon Simple Queue Service API Reference
+  [ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html) in the Amazon Simple Queue Service API Reference
+  [SetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SetQueueAttributes.html) in the Amazon Simple Queue Service API Reference

# Setting Visibility Timeout in Amazon SQS
<a name="examples-sqs-visibility-timeout"></a>

When a message is received in Amazon SQS, it remains on the queue until it’s deleted in order to ensure receipt. A message that was received, but not deleted, will be available in subsequent requests after a given *visibility timeout* to help prevent the message from being received more than once before it can be processed and deleted.

When using [standard queues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/standard-queues.html), visibility timeout isn’t a guarantee against receiving a message twice. If you are using a standard queue, be sure that your code can handle the case where the same message has been delivered more than once.

## Prerequisites
<a name="codeExamplePrereq"></a>

Before you begin, we recommend you read [Getting started using the AWS SDK for C\$1\$1](getting-started.md). 

Download the example code and build the solution as described in [Getting started on code examples](getting-started-code-examples.md). 

To run the examples, the user profile your code uses to make the requests must have proper permissions in AWS (for the service and the action). For more information, see [Providing AWS credentials](credentials.md).

## Set the Message Visibility Timeout upon Message Receipt
<a name="sqs-visibility-timeout-receipt"></a>

When you have received a message, you can modify its visibility timeout by passing its receipt handle in a [ChangeMessageVisibilityRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_change_message_visibility_request.html) that you pass to the SQSClient class’ `ChangeMessageVisibility` member function.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/ChangeMessageVisibilityRequest.h>
#include <aws/sqs/model/ReceiveMessageRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::Model::ChangeMessageVisibilityRequest request;
    request.SetQueueUrl(queue_url);
    request.SetReceiptHandle(messageReceiptHandle);
    request.SetVisibilityTimeout(visibilityTimeoutSeconds);

    auto outcome = sqsClient.ChangeMessageVisibility(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully changed visibility of message " <<
                  messageReceiptHandle << " from queue " << queue_url << std::endl;
    }
    else {
        std::cout << "Error changing visibility of message from queue "
                  << queue_url << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/change_message_visibility.cpp).

## More Info
<a name="more-info"></a>
+  [Visibility Timeout](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-visibility-timeout.html) in the Amazon Simple Queue Service Developer Guide
+  [SetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SetQueueAttributes.html) in the Amazon Simple Queue Service API Reference
+  [GetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_GetQueueAttributes.html) in the Amazon Simple Queue Service API Reference
+  [ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html) in the Amazon Simple Queue Service API Reference
+  [ChangeMessageVisibility](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ChangeMessageVisibility.html) in the Amazon Simple Queue Service API Reference
+  [ChangeMessageVisibilityBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ChangeMessageVisibilityBatch.html) in the Amazon Simple Queue Service API Reference

# Using Dead Letter Queues in Amazon SQS
<a name="examples-sqs-dead-letter-queues"></a>

Amazon SQS provides support for *dead letter queues*. A dead letter queue is a queue that other queues can target for messages that can’t be processed successfully. You can set aside and isolate these messages in the dead letter queue to determine why their processing did not succeed.

To create a dead letter queue, you must first create a *redrive policy*, and then set the policy in the queue’s attributes.

**Important**  
A dead letter queue must be the same type of queue (FIFO or standard) that the source queue is. It must also be created using the same AWS account and AWS Region as the source queue.

## Prerequisites
<a name="codeExamplePrereq"></a>

Before you begin, we recommend you read [Getting started using the AWS SDK for C\$1\$1](getting-started.md). 

Download the example code and build the solution as described in [Getting started on code examples](getting-started-code-examples.md). 

To run the examples, the user profile your code uses to make the requests must have proper permissions in AWS (for the service and the action). For more information, see [Providing AWS credentials](credentials.md).

## Create a Redrive Policy
<a name="sqs-dead-letter-queue-create-redrive-policy"></a>

A redrive policy is specified in JSON. To create it, you can use the JSON utility class provided with the AWS SDK for C\$1\$1.

Here is an example function that creates a redrive policy by providing it with the ARN of your dead letter queue and the maximum number of times the message can be received and not processed before it’s sent to the dead letter queue.

 **Includes** 

```
#include <aws/core/Aws.h>
#include <aws/core/utils/json/JsonSerializer.h>
```

 **Code** 

```
Aws::String MakeRedrivePolicy(const Aws::String &queueArn, int maxReceiveCount) {
    Aws::Utils::Json::JsonValue redrive_arn_entry;
    redrive_arn_entry.AsString(queueArn);

    Aws::Utils::Json::JsonValue max_msg_entry;
    max_msg_entry.AsInteger(maxReceiveCount);

    Aws::Utils::Json::JsonValue policy_map;
    policy_map.WithObject("deadLetterTargetArn", redrive_arn_entry);
    policy_map.WithObject("maxReceiveCount", max_msg_entry);

    return policy_map.View().WriteReadable();
}
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/dead_letter_queue.cpp).

## Set the Redrive Policy on your Source Queue
<a name="sqs-dead-letter-queue-set-redrive-policy"></a>

To finish setting up your dead letter queue, call the SQSClient class’ `SetQueueAttributes` member function with a [SetQueueAttributesRequest](https://docs.aws.amazon.com/sdk-for-cpp/latest/api/aws-cpp-sdk-sqs/html/class_aws_1_1_s_q_s_1_1_model_1_1_set_queue_attributes_request.html) object for which you’ve set the `RedrivePolicy` attribute with your JSON redrive policy.

 **Includes** 

```
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/SetQueueAttributesRequest.h>
#include <iostream>
```

 **Code** 

```
    Aws::SQS::Model::SetQueueAttributesRequest request;
    request.SetQueueUrl(srcQueueUrl);
    request.AddAttributes(
            Aws::SQS::Model::QueueAttributeName::RedrivePolicy,
            redrivePolicy);

    const Aws::SQS::Model::SetQueueAttributesOutcome outcome =
            sqsClient.SetQueueAttributes(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully set dead letter queue for queue  " <<
                  srcQueueUrl << " to " << deadLetterQueueARN << std::endl;
    }
    else {
        std::cerr << "Error setting dead letter queue for queue " <<
                  srcQueueUrl << ": " << outcome.GetError().GetMessage() <<
                  std::endl;
    }
```

See the [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sqs/dead_letter_queue.cpp).

## More Info
<a name="more-info"></a>
+  [Using Amazon SQS Dead Letter Queues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-dead-letter-queues.html) in the Amazon Simple Queue Service Developer Guide
+  [SetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SetQueueAttributes.html) in the Amazon Simple Queue Service API Reference