<|channel|>analysis<|message|>Need explain how to use Xerces to build XML. Provide code sample.<|end|>

<|start|>assistant<|channel|>final<|message|>## 1. What you’ll get

* A **single‑source** C++ program that builds a SEPA *pain.008.001.08* file (the one you pasted) from plain C++ data structures.
* The program uses **Xerces‑C** – the de‑facto XML library for C++ – to create the DOM, set attributes, and write the final document to disk.
* All logic is in one file (`sepa_builder.cpp`).  
  Compile with a modern compiler (g++, clang) linked against Xerces.

---

## 2. Prerequisites

| Item | Command (Ubuntu / Debian) | Notes |
|------|---------------------------|-------|
| **Xerces‑C** | `sudo apt-get install libxerces-c-dev` | On Windows you can download the pre‑built binaries or build from source. |
| **C++17 compiler** | `g++ -std=c++17 sepa_builder.cpp -lxerces-c -o sepa_builder` | Adjust include/link paths if Xerces is in a non‑standard location. |

> If you’re on macOS, use Homebrew:  
> `brew install xerces-c` and compile with `-I/usr/local/include -L/usr/local/lib`.

---

## 3. The Code

```cpp
/********************************************************************
 * sepa_builder.cpp – Build a pain.008.001.08 SEPA XML file
 * using Xerces‑C (DOM API).
 *
 * The program mirrors the example you posted, but all data is
 * provided through C++ structs so it can be adapted to read from DB,
 * CSV, or any other source.
 ********************************************************************/

#include <xercesc/util/PlatformUtils.hpp>
#include <xercesc/dom/DOM.hpp>
#include <xercesc/framework/LocalFileFormatTarget.hpp>

#include <iostream>
#include <string>
#include <vector>
#include <memory>   // std::unique_ptr

using namespace xercesc;

// ---------------------------------------------------------------------
// Helper to convert std::string -> XMLCh* (UTF‑16)
// ---------------------------------------------------------------------
static XMLCh* xmlString(const std::string& s) {
    return XMLString::transcode(s.c_str());
}

// ---------------------------------------------------------------------
// Data structures that hold the information we want in the XML
// ---------------------------------------------------------------------

struct MandateInfo {
    std::string mandateId;
    std::string dateOfSignature;   // YYYY-MM-DD
    bool        amendmentInd;
};

struct DirectDebitTx {
    std::string endToEndId;
    double      amount;             // EUR
    MandateInfo mandate;

    std::string debtorBIC;
    std::string debtorName;
    std::string debtorIBAN;
    std::string remittance;         // Ustrd

    // Optional: structured address (for non‑EWR debitors)
    struct Address {
        std::string streetNm, postCd, townNm, country;
    } *address = nullptr;          // NULL if not needed
};

struct PaymentInfo {
    std::string paymentInfId;
    std::vector<DirectDebitTx> txs;

    double ctrlSum() const {
        double s = 0.0;
        for (auto &t : txs) s += t.amount;
        return s;
    }
};

struct GroupHeader {
    std::string msgId, creationDateTime;   // ISO‑8601
    int         nbOfTxs;
    double      ctrlSum;
    std::string initiatorName;
};

// ---------------------------------------------------------------------
// Build the DOM document
// ---------------------------------------------------------------------
std::unique_ptr<DOMDocument> buildSEPA(const GroupHeader& gh,
                                       const PaymentInfo& pi)
{
    // 1. Create a new empty document
    auto doc = std::make_unique<DOMDocument>();

    /* ----- Document root --------------------------------------------- */
    XMLCh* nsURI   = xmlString("urn:iso:std:iso:20022:tech:xsd:pain.008.001.08");
    DOMElement* root =
        doc->createElementNS(nsURI, xmlString("Document"));
    // xmlns:xsi
    doc->setDocumentElement(root);
    root->setAttribute(xmlString("xmlns:xsi"),
                       xmlString("http://www.w3.org/2001/XMLSchema-instance"));

    /* ----- CstmrDrct