#pragma section-numbers off
#pragma camelcase off

= SDL_SetAssertionHandler =
Use this function to set an application-defined assertion handler.

<<TableOfContents()>>

== Syntax ==
{{{#!highlight cpp
void SDL_SetAssertionHandler(SDL_AssertionHandler handler,
                             void*                userdata)
}}}

== Function Parameters ==
||'''handler'''||the function to call when an assertion fails or NULL for the default handler; see [[#Remarks|Remarks]] for details||
||'''userdata'''||a pointer that is passed to '''handler'''||

== Code Examples ==
{{{#!highlight cpp
You can add your code example here
}}}

== Remarks ==
This function allows an application to show its own assertion UI and/or force the response to an assertion failure. If the application doesn't provide this, SDL will try to do the right thing, popping up a system-specific GUI dialog, and probably minimizing any fullscreen windows.

The function prototype for '''handler''' is:
{{{#!highlight cpp
SDL_AssertState YourAssertionHandler(const SDL_AssertData* data,
                                     void*                 userdata)
}}}
 . where `YourAssertionHandler` is the name of your function and its parameters are:
 ||`data`||a pointer to the [[SDL_AssertData]] structure corresponding to the current assertion||
 ||`userdata`||what was passed as '''userdata''' to [[SDL_SetAssertionHandler]]()||

 .This callback should return an [[SDL_AssertState]] value indicating how to handle the assertion failure.

This callback may fire from any thread, but it runs wrapped in a mutex, so it will only fire from one thread at a time.

This callback is NOT reset to SDL's internal handler upon [[SDL_Quit]]()!

== Related Functions ==
 .[[SDL_GetAssertionHandler]]

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[[CategoryAPI]], [[CategoryAssertions]]