---
title: "Display a screen on a large screen terminal - C"
url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/display-a-screen-on-a-large-screen-terminal-c"
source_url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/display-a-screen-on-a-large-screen-terminal-c.md"
canonical: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/display-a-screen-on-a-large-screen-terminal-c"
last_modified: "2026-05-23T12:56:20+02:00"
language: "en"
---

# Display a screen on a large screen terminal - C

[View source](/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/extras-c-library/display-a-screen-on-a-large-screen-terminal-c.md)

## Implement the callback

Implement the callback based on the signature in the** show\_screen\_extern.h** file and pass this as a parameter of the `show_screen` call. For more information on how to do this, see [Implement callbacks](/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/calls-and-callbacks-c-library/implement-callbacks).

### Code example

```cpp
void show_screen_CB(show_screen_response *p, void *echo_struct){
app_context_t * POS = (app_context_t *)echo_struct;

}
```

## Allocate the request structure

Use `show_screen_allocate` to allocate, initialize and return a `show_screen_request` structure. Populate the request by performing string duplication.

If you want the data for later use, retain it, or it will be released automatically.

## Call the show\_screen function

Call the `show_screen` function to display specific screens prior to the processing the tender or terminals with large screens (MX925, MX915). Use this function to display order items on a virtual receipt.

### Parameters

| Value                 | Description                                                                                                 |
| --------------------- | ----------------------------------------------------------------------------------------------------------- |
| `show_tender_request` | Pointer to the `show_screen_request` struct, this struct contains all the input parameters for this call.   |
| `show_screen_CB`      | Pointer to the callback function in the POS that will be called with the results of the `show_screen` call. |

### Code example

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

```cpp
ADYLibraryResult show_screen(show_screen_request * show_screen_request_ptr, void(*callback_function)(show_screen_response *, void *), void * echo_struct);
```

## Handle the callback

The `show_screen_CB` returns the immediate response to the call and a pointer to the POS-defined echo struct.

### Parameters

| Value                  | Description                                                                                                                                                                                     |
| ---------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `show_screen_response` | The immediate response to the show\_screen call, which includes the ID and status of the screen, and the result of the 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 in response to the call. |