---
name: "SDL_IN_BYTECAP"
section: "3"
platform: "linux"
package: "libsdl3-doc"
version: "3.2.10+ds-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/SDL_IN_BYTECAP"
---

# SDL\_IN\_BYTECAP(3)

Macro that annotates function params with input buffer size.

## NAME

SDL\_IN\_BYTECAP - Macro that annotates function params with input buffer size.

## HEADER FILE

Defined in SDL3/SDL\_stdinc.h

## SYNOPSIS

```
#include "SDL3/SDL.h"
```

**#define SDL\_IN\_BYTECAP(x) \_In\_bytecount\_(x)**

## DESCRIPTION

If we were to annotate **memcpy** :

-

  ```
  void *memcpy(void *dst, SDL_IN_BYTECAP(len) const void *src, size_t len);
  ```

This notes that **src** should be **len** bytes in size and is only read by the function. The compiler or other analysis tools can warn when this doesn't appear to be the case.

On compilers without this annotation mechanism, this is defined to nothing.

## AVAILABILITY

This macro is available since SDL 3.2.0.