---
title: "Start Alipay and WeChat Pay transactions"
url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/start-alipay-and-wechat-pay-transactions-c"
source_url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/start-alipay-and-wechat-pay-transactions-c.md"
canonical: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/start-alipay-and-wechat-pay-transactions-c"
last_modified: "2026-05-24T12:54:31+02:00"
language: "en"
---

# Start Alipay and WeChat Pay transactions

[View source](/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/start-alipay-and-wechat-pay-transactions-c.md)

## Prototype the callback

Prototype the `create_new_tender_CB` and pass this as a parameter of the function pointer to the `create_special_tender` call. 

### Code example

The callback function declaration is:

```cpp
void create_new_tender_CB(create_tender_response *response, void *echo_struct){
    app_context_t *sPOS = (app_context_t *)echo_struct;
if (response->tender_reference) {
        safe_strdup(&sPOS->tender_reference, response->tender_reference);
        sPOS->pending_callback = 0; //mark ok......
    } else {
        sPOS->pending_callback = -1;
}
```

## Allocate and populate request structure

Use `create_special_tender_request` to allocate memory for an `special_tender_request` structure. Populate the request by performing string duplication and filling heap allocated strings. If you want the data for later use, retain it, or it will be released automatically.

```cpp
special_tender_request *request = create_special_tender_request();
    if (request) {
         request->reference = strdup("Simple transaction");
         request->merchant_account = strdup(sPOS->merchant_account);
         request->terminal_id = strdup(sPOS->terminal_id);
         request->amount_currency = strdup(sPOS->currency);
         request->amount_value = sPOS->amount;
         request->transaction_type = strdup("payment");
         request->payment_method_type = strdup("alipay");
 
```

## Add and remove special options

Special options are dictionary key value pairs. This information is passed directly to the PED, which interprets it.

Use `special_tender_add_option` to set  special options, passing the request along with key value pairs. Use `special_tender_rm_option` to remove the set options.

## Call the create\_special\_tender Function

Call the `create_special_tender` function to Initiate the sale transaction, which triggers any relevant callbacks, and pass in the request that was previously allocated.

The POS waits for the final state and the  `status_tender_final`  callback to report the final result of the transaction, even if a cancel request has been issued. The reason for this is that the transaction might already be in a state in which a cancel is not possible.

The sale transaction includes the merchant account information, as this is used to register PEDs for multiple merchant accounts, and transactions can be performed on more than one of these merchant accounts.

## Parameters

| Value                  | Description                                                                                                                                                             |
| ---------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `request`              | Pointer to the `special_tender_request` struct, this struct contains all the input parameters for this call.                                                            |
| `create_new_tender_CB` | Pointer to the callback function in the POS that will be called with the results of the create special tender call                                                      |
| `echo_struct`          | Pointer to a POS defined struct. Returned in the callback. It can be used to share a POS data struct between the call to the library and the callback from the library. |

### Code example

The declaration of the call to start a transaction is as follows:

```cpp
result = create_special_tender(request, create_new_tender_CB, sPOS);
```

## Handle the callback

Handle the `create_new_tender_CB` to check if the transaction was accepted by the terminal by checking if `tender_reference` was populated by the library. 

```cpp
 if (response->tender_reference) {
  safe_strdup(&sPOS->tender_reference, response->tender_reference);
  sPOS->pending_callback = 0; //mark ok......
 } else {
  sPOS->pending_callback = -1;
 }
```

Check the result by getting information from the `create_tender_response`.

The POS needs to wait for the `create_new_tender_CB` to happen, before it can continue with other functions.  After the `create_new_tender_CB` is returned, the system returns a number of other callbacks. Finally, the system returns the final callback that contains the final transaction result. Another transaction can only be started when the final transaction result is received.

### Parameters

| Data element             | Description                                                                                                                                                                                           |
| ------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `create_tender_response` | A unique reference for the transaction that is generated by the PED device. This reference is used for subsequent actions on the transaction. For a list of parameters, see `create_tender_response`. |
| `echo_struct`            | Pointer to a user-defined struct. Returned in the callback. It can be used to share a POS data struct between the call to the library and the callback from the library in response to the call.      |

The `create_new_tender_CB` is a callback to the creation of a tender, but does not represent the status or result of the transaction. The result is returned in `tender_finished_CB`.