Return to Recursion

“CPP recursion - (1) invoking a function that is called (directly or indirectly) from that same function— e.g., int f(int n) { return n > 0 ? n * f(n-1) : 1; } — or (2) defining an entity in terms of itself, e.g., a type list (see Section 2.1.“Variadic Templates” on page 873). Variadic Templates (875)” (EMCppSfe 2021)“ (EMCppSfe 2021)

CPP Recursion equivalents: Compare and contrast for Python, PowerShell, Bash, Rust, Golang, JavaScript, TypeScript, Java, Kotlin, Scala, Clojure, Haskell, F Sharp, Erlang, Elixir, Swift, C Sharp, CPP, C Language, Zig, PHP, Ruby, Dart, Microsoft T-SQL, Oracle PL/SQL, PL/pgSQL, Julia, R Language, Perl, COBOL, Fortran, Ada, VBScript, Basic, Pascal.

CPP Recursion is a powerful programming paradigm supported natively, allowing functions to call themselves for solving problems like divide-and-conquer, tree traversal, and dynamic programming. Below is a comparison of recursion support and equivalents across 35 programming languages.

• Recursion: Fully supported with a simple syntax.
• Strengths: Readable and intuitive for recursive algorithms.
• Weaknesses: No tail call optimization, leading to potential stack overflow for deep recursion.

• Recursion: Supported via function calls.
• Strengths: Easy to implement for small-scale tasks.
• Weaknesses: Lacks advanced features like tail call optimization.

• Recursion: Limited support using function calls in scripts.
• Strengths: Possible for basic use cases.
• Weaknesses: Prone to stack overflow and inefficient for deep recursion.

• Recursion: Fully supported with strict safety checks.
• Strengths: Guarantees memory safety; supports functional paradigms.
• Weaknesses: Verbose for certain recursive constructs.

• Recursion: Fully supported.
• Strengths: Efficient stack handling; integrates well with concurrency.
• Weaknesses: No tail call optimization, leading to stack overflow in some cases.

• Recursion: Fully supported.
• Strengths: Asynchronous recursion supported via `async`/`await`.
• Weaknesses: No built-in tail call optimization in most engines.

• Recursion: Same as JavaScript, with type safety.
• Strengths: Enhances reliability through type annotations.
• Weaknesses: Limited beyond JavaScript’s recursion constraints.

• Recursion: Fully supported.
• Strengths: Handles recursive algorithms well.
• Weaknesses: No tail call optimization, and verbose syntax for functional tasks.

• Recursion: Supported with functional syntax.
• Strengths: Adds concise syntax for recursive solutions.
• Weaknesses: No tail call optimization unless explicitly using `tailrec`.

• Recursion: Fully supported with functional paradigms.
• Strengths: Tail call optimization and immutability ensure safety.
• Weaknesses: Verbose for certain use cases.

• Recursion: Supported with `recur` for tail call optimization.
• Strengths: Functional-first approach simplifies recursion.
• Weaknesses: Requires `recur` for optimized tail recursion.

• Recursion: Integral to functional programming.
• Strengths: Tail call optimization and lazy evaluation.
• Weaknesses: Learning curve for recursive idioms.

• Recursion: Fully supported with tail call optimization in functional contexts.
• Strengths: Works seamlessly with functional paradigms.
• Weaknesses: Limited adoption outside the .NET ecosystem.

• Recursion: Integral for iteration, as loops are not native.
• Strengths: Fault-tolerant and lightweight processes.
• Weaknesses: Verbose for deeply recursive algorithms.

• Recursion: Same as Erlang.
• Strengths: Simple for distributed and concurrent systems.
• Weaknesses: Limited to BEAM virtual machine.

• Recursion: Fully supported.
• Strengths: Intuitive syntax for recursive problems.
• Weaknesses: No built-in tail call optimization.

• Recursion: Supported, including `async` recursion.
• Strengths: Works well in combination with .NET frameworks.
• Weaknesses: No tail call optimization by default.

• Recursion: Fully supported.
• Strengths: High performance and low-level control.
• Weaknesses: Prone to stack overflow without proper checks.

• Recursion: Supported with compile-time checks.
• Strengths: Combines recursion with memory safety.
• Weaknesses: Limited support for functional recursion patterns.

• Recursion: Fully supported.
• Strengths: Easy to implement for web-based workflows.
• Weaknesses: Prone to stack overflow in deep recursion scenarios.

• Recursion: Supported but not idiomatic.
• Strengths: Useful for functional-style algorithms.
• Weaknesses: No tail call optimization, and iterative solutions are preferred.

• Recursion: Fully supported.
• Strengths: Combines recursion with modern web and UI workflows.
• Weaknesses: No tail call optimization.

• Recursion: Supported via Common Table Expressions (CTEs).
• Strengths: Ideal for hierarchical data queries.
• Weaknesses: Limited outside database-specific contexts.

• Recursion: Supported in functions and procedures.
• Strengths: Excellent for database-side logic.
• Weaknesses: Limited for general-purpose recursive algorithms.

• Recursion: Supported in PostgreSQL with recursive queries.
• Strengths: Optimized for database workflows.
• Weaknesses: No support for non-database recursion.

• Recursion: Fully supported.
• Strengths: Optimized for numerical and scientific computations.
• Weaknesses: Limited for deeply recursive algorithms.

• Recursion: Supported but not idiomatic.
• Strengths: Useful for certain data transformations.
• Weaknesses: Inefficient for deep recursion.

• Recursion: Fully supported.
• Strengths: Useful for lightweight text processing tasks.
• Weaknesses: Inefficient for complex recursive algorithms.

• Recursion: Limited or unsupported in traditional COBOL.
• Strengths: Reliable for iterative logic.
• Weaknesses: Not designed for recursive workflows.

• Recursion: Fully supported in modern Fortran versions.
• Strengths: High performance for numerical tasks.
• Weaknesses: Verbose for complex recursion.

• Recursion: Fully supported.
• Strengths: Strong typing ensures safety.
• Weaknesses: Verbose syntax for recursive functions.

• Recursion: Supported.
• Strengths: Easy to use for small-scale problems.
• Weaknesses: Inefficient for large recursive tasks.

• Recursion: Supported in modern implementations.
• Strengths: Beginner-friendly.
• Weaknesses: Inefficient for deep recursion or complex problems.

• Recursion: Fully supported.
• Strengths: Strong typing simplifies recursive logic.
• Weaknesses: Verbose for deeply recursive workflows.

This table provides a comprehensive comparison of recursion support across 35 languages, showcasing their strengths and weaknesses in handling recursive programming.

ChatGPT o1:

CPP (introduced in the year 1985) recursion is a fundamental programming technique that allows a function to call itself. By doing so, it breaks down complex problems into more manageable subproblems, each closely resembling the overall task. When the function finally reaches a base case, it starts returning values that rebuild the final result through a series of recursive calls.

In CPP, implementing recursion involves using a carefully chosen function signature and ensuring that each recursive call progresses toward a terminating condition. Without such a base case, the function may continue to call itself indefinitely, eventually causing a stack overflow error. This approach is supported by modern compilers like GNU GCC (introduced in the year 1987), which properly allocate stack memory for each function call.

One of the primary benefits of recursion is its ability to create clean and elegant solutions for problems such as tree traversals, divide-and-conquer algorithms, and complex combinatorial computations. Instead of manually implementing intricate loops or managing extra data structures, a recursive function often maps directly to the theoretical description of the algorithm. This can make the resulting source code easier to read and maintain.

However, recursion is not always the most efficient method. Each recursive call requires additional memory on the call stack, and if the problem size grows large, this can lead to performance overhead. In some cases, an iterative solution using loops might be more space and time efficient. Nevertheless, understanding how to use recursion is a key skill for any CPP developer.

When working with CPP recursion, it can be helpful to use a debugger to step through each function call and observe the state of local variables. Integrated Development Environments (IDE) provide features like breakpoints, watch variables, and call stack inspection, making it easier to diagnose issues. Although IDE itself is not a product introduced in a specific year, its widespread use on various operating systems like UNIX (introduced in the year 1969), Windows (introduced in the year 1985), and macOS (introduced in the year 2001) simplifies the process.

To master CPP recursion, start with simple examples, such as computing the factorial of a number or finding the greatest common divisor of two integers. Gradually move on to more complex problems that require multiple recursive calls and careful planning. Experience gained through experimentation and practice will help you develop an intuition for when to use recursion effectively.

As you gain confidence, explore advanced techniques like memoization or tail recursion optimization. While classic recursion repeatedly builds new stack frames, tail recursion optimization can reuse a single stack frame in certain circumstances, reducing overhead. This approach is dependent on the capabilities of the CPP compiler, which must detect and optimize these cases.

Ultimately, CPP recursion is not just a neat trick, but a powerful concept that enables more intuitive solutions for a range of computational challenges. By understanding its mechanics, benefits, and limitations, you can write more expressive source code and tackle sophisticated algorithms with confidence.

Below is an example demonstrating how CPP Recursion can be integrated into a WebAssembly (Wasm, introduced in the year 2017) environment. Here, a CPP (introduced in the year 1985) function uses recursion to calculate the factorial of a given integer. By compiling the CPP source code into Wasm using Emscripten (introduced in the year 2010), it can be executed efficiently in a web browser or any WebAssembly runtime. This approach shows how advanced programming techniques, such as recursion, can be seamlessly integrated into Wasm-based deployments, offering near-native performance and portability across various operating systems and architectures.

Below is a sample CPP source code snippet that will be compiled to a Wasm module:

1. include <iostream>

int factorial(int n) {

   if (n <= 1) {
       return 1;
   }
   return n * factorial(n - 1);

int main() {

   int value = 10;
   int result = factorial(value);
   std::cout << "Factorial of " << value << " is " << result << std::endl;
   return 0;

When compiled with Emscripten, this CPP application produces a Wasm module and a corresponding JavaScript (introduced in the year 1995) glue code file. Loading these files in a web browser or with a Wasm runtime allows you to run the recursive factorial computation natively within the browser environment. While the underlying concept of recursion remains the same as in any CPP program, the Wasm execution model ensures secure, sandboxed, and efficient execution. This example highlights how established CPP techniques, like recursion, can be adapted and utilized within modern Wasm ecosystems.

Below is an example demonstrating how to integrate CPP Recursion into a CPP (introduced in the year 1985) Web Server built using the POCO (introduced in the year 2005) C++ libraries. In this example, a recursive function computes the factorial of a given number and returns the result as part of an HTML (introduced in the year 1993) HTTP (introduced in the year 1991) response. By combining CPP Recursion with the POCO Net library to create a HTTPServer and a custom HTTPRequestHandler, you can serve dynamically generated content that showcases the elegance and power of recursive programming techniques within a real-world web server environment.

Below is a sample CPP source code snippet. It assumes you have installed the POCO libraries and configured your build environment appropriately.

1. include <Poco/Net/HTTPRequestHandler.h>
2. include <Poco/Net/HTTPRequestHandlerFactory.h>
3. include <Poco/Net/HTTPServer.h>
4. include <Poco/Net/HTTPServerRequest.h>
5. include <Poco/Net/HTTPServerResponse.h>
6. include <Poco/Net/ServerSocket.h>
7. include <Poco/Util/ServerApplication.h>
8. include <Poco/Util/Subsystem.h>
9. include <iostream>
10. include <string>

int factorial(int n) {

   if (n <= 1) {  
       return 1;  
   }  
   return n * factorial(n - 1);  

class RecursiveRequestHandler : public HTTPRequestHandler { public:

   void handleRequest([[Poco::Net::HTTPServerRequest]]& request, [[Poco::Net::HTTPServerResponse]]& response) override {  
       int value = 10;  
       int result = factorial(value);  
       response.setContentType("text/html");  
       response.setStatus([[Poco::Net::HTTPResponse]]::HTTP_OK);  
       std::ostream& ostr = response.send();  
       ostr << "";  
       ostr << "
Factorial of " << value << " is " << result << "
";  
   }  

class RecursiveRequestHandlerFactory : public HTTPRequestHandlerFactory { public:

   [[Poco::Net::HTTPRequestHandler]]* createRequestHandler(const [[Poco::Net::HTTPServerRequest]]&) override {  
       return new [[RecursiveRequestHandler]];  
   }  

class MyRecursiveWebServerApp : public ServerApplication { protected:

   int main(const std::vector&) {  
       [[Poco::Net::ServerSocket]] socket(8080);  
       [[Poco::Net::HTTPServer]] server(new [[RecursiveRequestHandlerFactory]], socket, new [[Poco::Net::HTTPServerParams]]);  
       server.start();  
       waitForTerminationRequest();  
       server.stop();  
       return Application::EXIT_OK;  
   }  

int main(int argc, char** argv) {

   [[MyRecursiveWebServerApp]] app;  
   return app.run(argc, argv);  

In this code, the factorial function demonstrates CPP Recursion by calling itself until it reaches a base case. The RecursiveRequestHandler uses this recursive result to generate a dynamic HTML page. When the MyRecursiveWebServerApp is run, the HTTPServer listens on port 8080, and navigating to http://localhost:8080/ in a web browser displays the factorial of 10 computed via recursion. This example illustrates how the POCO libraries can seamlessly integrate with classic CPP programming techniques, such as recursion, to build flexible and maintainable web server solutions.

Below is an example demonstrating how to use CPP Recursion in conjunction with the AWS SDK for CPP (introduced in the year 2015) to recursively list objects in an Amazon S3 bucket. CPP (introduced in the year 1985) recursion is employed here to handle pagination when listing large numbers of objects. The AWS SDK for CPP provides APIs to interact with Amazon S3 (introduced in the year 2006), and by implementing a recursive function, it is possible to automatically handle the continuation tokens returned by Amazon S3 when the number of objects exceeds one page of results. This approach simplifies the code and makes it easier to maintain.

Before running this code, ensure that you have properly installed and configured the AWS SDK for CPP according to the Amazon Web Services setup guidelines. Also, make sure you have valid AWS credentials and the appropriate permissions to access the specified S3 bucket.

1. include <aws/core/Aws.h>
2. include <aws/s3/S3Client.h>
3. include <aws/s3/model/ListObjectsV2Request.h>
4. include <aws/s3/model/ListObjectsV2Result.h>
5. include <iostream>
6. include <string>

void ListAllObjects(const Aws::S3::S3Client& s3Client, const std::string& bucketName, const std::string& continuationToken = ”“) {

   Aws::S3::Model::ListObjectsV2Request request;  
   request.SetBucket(bucketName.c_str());  
   if (!continuationToken.empty()) {  
       request.SetContinuationToken(continuationToken.c_str());  
   }

   auto outcome = s3Client.ListObjectsV2(request);  
   if (outcome.IsSuccess()) {  
       const auto& result = outcome.GetResult();  
       for (const auto& object : result.GetContents()) {  
           std::cout << "Object key: " << object.GetKey() << std::endl;  
       }

       if (result.GetIsTruncated() && !result.GetNextContinuationToken().empty()) {  
           // Recursively call the function if more objects are available  
           ListAllObjects(s3Client, bucketName, result.GetNextContinuationToken());  
       }  
   } else {  
       std::cerr << "Error listing objects: " << outcome.GetError().GetMessage() << std::endl;  
   }  

int main(int argc, char** argv) {

   Aws::SDKOptions options;  
   Aws::InitAPI(options);  
   {  
       Aws::S3::S3Client s3Client;  
       std::string bucketName = "my-example-bucket";  
       ListAllObjects(s3Client, bucketName);  
   }  
   Aws::ShutdownAPI(options);  
   return 0;  

In this code, the ListAllObjects function uses recursion to handle multiple pages of results from Amazon S3. After listing objects and checking whether the results are truncated, the function calls itself with the NextContinuationToken provided by Amazon S3. This ensures that the program continues to fetch and print objects until there are no more objects left to list. By combining CPP Recursion with the AWS SDK for CPP, developers can build scalable and maintainable code that handles complex pagination scenarios with ease.

Below is an example demonstrating how to use CPP Recursion in conjunction with the Azure SDK for CPP (introduced in the year 2020) to recursively list blobs in an Azure Storage (introduced in the year 2010) blob container. CPP (introduced in the year 1985) recursion is employed here to handle pagination when listing large numbers of blobs. The Azure SDK for CPP provides APIs to interact with Azure (introduced in the year 2010) Storage services, and by implementing a recursive function, it is possible to automatically handle the continuation tokens returned by Azure Storage when the number of blobs exceeds one page of results. This approach simplifies the code and makes it easier to maintain.

Before running this code, ensure that you have properly installed and configured the Azure SDK for CPP according to the Microsoft (introduced in the year 1975) setup guidelines. Also, make sure you have valid Azure credentials and the appropriate permissions to access the specified blob container.

1. include <azure/core.hpp>
2. include <azure/identity.hpp>
3. include <azure/storage/blobs.hpp>
4. include <iostream>
5. include <string>

void ListAllBlobs(const Azure::Storage::Blobs::BlobContainerClient& containerClient, const std::string& continuationToken = ”“) {

   Azure::Storage::Blobs::ListBlobsOptions options;  
   options.ContinuationToken = continuationToken;  

   auto response = containerClient.ListBlobs(options);  
   for (auto& blob : response.Blobs) {  
       std::cout << "Blob name: " << blob.Name << std::endl;  
   }

   if (!response.NextPageToken.empty()) {  
       // Recursively call the function if more blobs are available  
       ListAllBlobs(containerClient, response.NextPageToken);  
   }  

int main(int argc, char** argv) {

   Azure::Core::Credentials::TokenCredentialOptions credentialOptions;  
   auto credential = std::make_shared(credentialOptions);  
   std::string containerUrl = "https://myaccount.blob.core.windows.net/mycontainer";  
   Azure::Storage::Blobs::BlobContainerClient containerClient(containerUrl, credential);

   ListAllBlobs(containerClient);  
   return 0;  

In this code, the ListAllBlobs function uses CPP Recursion to handle multiple pages of results from Azure Storage. After listing blobs and checking whether more pages are available, the function calls itself with the NextPageToken provided by Azure Storage. This ensures that the program continues to fetch and print objects until there are no more blobs left to list. By combining CPP Recursion with the Azure SDK for CPP, developers can build scalable and maintainable code that handles complex pagination scenarios within the Azure environment.

Below is an example demonstrating how to use CPP Recursion in conjunction with the Google Cloud CPP Client Libraries (introduced in the year 2019) to recursively list objects in a Google Cloud Storage (introduced in the year 2010) bucket. CPP (introduced in the year 1985) recursion is employed here to handle pagination when listing large numbers of objects. The Google Cloud CPP Client Libraries provide APIs to interact with Google Cloud Platform (introduced in the year 2008) services like Google Cloud Storage, and by implementing a recursive function, it is possible to automatically handle the continuation tokens when the number of objects exceeds one page of results. This approach simplifies the code and makes it easier to maintain.

Before running this code, ensure that you have properly installed and configured the Google Cloud CPP Client Libraries according to Google (introduced in the year 1998) setup guidelines. Also, make sure you have valid credentials and the appropriate permissions to access the specified Google Cloud Storage bucket.

1. include “google/cloud/storage/client.h”
2. include <iostream>
3. include <string>

void ListAllObjects(google::cloud::storage::Client& client, const std::string& bucket_name, const std::string& page_token = ”“) {

   google::cloud::storage::ListObjectsReader reader = client.ListObjects(bucket_name, google::cloud::storage::ListObjectsOptions().set_page_token(page_token));  

   std::string next_page_token;  
   for (auto const& object_metadata : reader) {  
       if (!object_metadata) {  
           std::cerr << "Error listing objects: " << object_metadata.status() << "\n";  
           return;  
       }  
       std::cout << "Object name: " << object_metadata->name() << "\n";  
   }  

   // Extract the next page token if there is one
   next_page_token = reader.NextPageToken();  
   if (!next_page_token.empty()) {  
       // Recursively call the function if more objects are available  
       ListAllObjects(client, bucket_name, next_page_token);  
   }  

int main(int argc, char** argv) {

   // Assumes that application default credentials are set up  
   google::cloud::storage::Client client = google::cloud::storage::Client::CreateDefaultClient().value();  
   std::string bucket_name = "my-example-bucket";  
   ListAllObjects(client, bucket_name);  
   return 0;  

In this code, the ListAllObjects function uses CPP Recursion to handle multiple pages of results from Google Cloud Storage. After listing objects and checking whether more pages are available, the function calls itself with the newly provided page token. This ensures that the program continues to fetch and print objects until there are no more objects left to list. By combining CPP Recursion with the Google Cloud CPP Client Libraries, developers can build scalable and maintainable code that handles complex pagination scenarios within the Google Cloud Platform environment.

Below is an example demonstrating how to use CPP Recursion with the Kubernetes Engine API CPP Client Library (introduced in the year 2021) to list Google Kubernetes Engine (GKE, introduced in the year 2015) clusters across multiple locations. In this scenario, CPP (introduced in the year 1985) recursion is used to handle a list of GCP (Google Cloud Platform, introduced in the year 2008) locations and print out the clusters in each one. While this example does not rely on pagination, it demonstrates how a recursive approach can be used to systematically process multiple inputs. The Kubernetes Engine API CPP Client Library provides APIs to interact with GKE, and by implementing a recursive function, it is possible to iterate through multiple locations seamlessly.

Before running this code, ensure that you have installed and configured the Kubernetes Engine API CPP Client Library as described in the official documentation. Also, make sure you have valid Google (introduced in the year 1998) credentials and permissions to access the specified GKE clusters.

1. include “google/cloud/container/v1/cluster_manager_client.h”
2. include <iostream>
3. include <string>
4. include <vector>

void ListClustersInLocations(google::cloud::container::v1::ClusterManagerClient& client,

                            const std::string& project_id,  
                            const std::vector& locations,  
                            std::size_t index = 0) {  
   if (index >= locations.size()) {  
       return;  
   }

   std::string parent = "projects/" + project_id + "/locations/" + locations[index];  
   auto response = client.ListClusters(parent);  
   if (!response) {  
       std::cerr << "Error listing clusters in " << locations[index] << ": " << response.status() << "\n";  
   } else {  
       for (auto const& cluster : response->clusters()) {  
           std::cout << "Cluster name: " << cluster.name() << " in location " << locations[index] << "\n";  
       }  
   }

   // Recursively call the function for the next location  
   ListClustersInLocations(client, project_id, locations, index + 1);  

int main(int argc, char** argv) {

   // Replace with your actual project ID and list of locations  
   std::string project_id = "my-gcp-project";  
   std::vector locations = {"us-central1", "us-east1", "europe-west1"};

   auto client = google::cloud::container::v1::ClusterManagerClient(google::cloud::container::v1::MakeClusterManagerConnection());
   ListClustersInLocations(client, project_id, locations);  
   return 0;  

In this code, the ListClustersInLocations function uses CPP Recursion to iterate over a vector of locations. For each location, it retrieves the clusters within that location using the Kubernetes Engine API CPP Client Library and prints their names. After processing the current location, the function recursively calls itself with the next index until all locations have been processed. By integrating CPP Recursion with the Kubernetes Engine API CPP Client Library, developers can create organized and maintainable code for interacting with GKE clusters across multiple locations.

Below is an example demonstrating how to use CPP Recursion with the HashiCorp Vault (HashiCorp introduced in the year 2012, HashiCorp Vault introduced in the year 2015) to retrieve secrets using the libvault (CPP library for HashiCorp Vault introduced in the year 2017), which is hosted at https://github.com/abedra/libvault. In this example, CPP (introduced in the year 1985) recursion is used to handle situations where a secret retrieval might need multiple attempts. The code defines a recursive function that tries to read a secret from HashiCorp Vault, and if the secret is not found or an error occurs, it retries a limited number of times until it either succeeds or exhausts the limit.

This approach can be helpful when dealing with dynamic secret generation, slow responses, or temporary network issues. By leveraging recursion, the code remains clean and maintainable, while still allowing multiple attempts at retrieving the desired secret.

1. include <iostream>
2. include <string>
3. include “vault.h” // Assumes that libvault provides a header file named vault.h

int RetrieveSecretRecursive(vault::Client& client, const std::string& secret_path, int attempts) {

   if (attempts <= 0) {  
       std::cerr << "No more attempts left to retrieve the secret." << std::endl;  
       return 1;  
   }

   auto response = client.read(secret_path);  
   if (!response) {  
       std::cerr << "Error retrieving secret: " << secret_path << ". Attempts remaining: " << attempts - 1 << std::endl;  
       return RetrieveSecretRecursive(client, secret_path, attempts - 1);  
   }

   // If successful, print the secret (for demonstration purposes)  
   std::cout << "Successfully retrieved secret from: " << secret_path << std::endl;  
   for (auto const& kv : response.value().data) {  
       std::cout << "Key: " << kv.first << " Value: " << kv.second << std::endl;  
   }

   return 0;  

int main(int argc, char** argv) {

   std::string vault_addr = "http://127.0.0.1:8200";  
   std::string token = "myroot";  
   vault::Config config;  
   config.address = vault_addr;  
   vault::Client client(config);  
   client.set_token(token);

   std::string secret_path = "secret/my_example_secret";  
   // Attempt to retrieve the secret up to 5 times  
   int result = RetrieveSecretRecursive(client, secret_path, 5);

   return result;  

In this code, the RetrieveSecretRecursive function uses CPP Recursion to handle multiple attempts at reading a secret from HashiCorp Vault. If the first attempt fails, it calls itself again with one fewer attempt until it either succeeds or runs out of attempts. By combining CPP Recursion with the libvault CPP library for HashiCorp Vault, developers can build resilient and maintainable code that gracefully handles transient failures or delays when interacting with HashiCorp Vault.

Below is an example demonstrating how to use CPP Recursion within a CPP (introduced in the year 1985) DevOps (introduced in the year 2009) CLI (introduced in the year 1960) automation scenario, utilizing the CLIUtils CLI11 CPP library (introduced in the year 2017) hosted at https://github.com/CLIUtils/CLI11. In this example, CPP Recursion is employed to compute the factorial of a given number passed as a command-line argument. The use of recursion simplifies the logic for complex computations often needed in DevOps workflows where tasks may need to be performed repeatedly until a desired result is obtained.

By combining CPP Recursion with CLIUtils CLI11, a developer can create a flexible command-line application that can be integrated into DevOps pipelines. This approach allows the tool to be easily scripted, automated, and orchestrated across various environments, enhancing the maintainability and scalability of your DevOps processes.

1. include “CLI/CLI.hpp”
2. include <iostream>
3. include <string>
4. include <cstdlib>

int factorial(int n) {

   if (n <= 1) {  
       return 1;  
   }  
   return n * factorial(n - 1);  

int main(int argc, char** argv) {

   CLI::App app{"[[CPP DevOps CLI automation]] with [[CPP Recursion]] and [[CLIUtils CLI11]]"};  
   int value;  
   app.add_option("-n,--number", value, "Number to compute factorial")->required();  

   try {  
       app.parse(argc, argv);  
   } catch (const CLI::ParseError &e) {  
       return app.exit(e);  
   }

   int result = factorial(value);  
   std::cout << "Factorial of " << value << " is " << result << std::endl;  
   return 0;  

In this code, the factorial function uses CPP Recursion to repeatedly call itself until it reaches a base case. The CLIUtils CLI11 library is used to parse the command-line arguments, ensuring that the user provides a valid integer. This combination of CPP Recursion and CLI tooling exemplifies how complex computations can be made accessible, scriptable, and automatable, making them ideal for a wide range of DevOps workflows.