---
name: "explain_vsnprintf_or_die"
section: "3"
platform: "linux"
package: "libexplain-dev"
version: "1.4.D001-16"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/explain_vsnprintf_or_die"
---

# explain\_vsnprintf\_or\_die(3)

formatted output conversion and report errors

## NAME

explain\_vsnprintf\_or\_die - formatted output conversion and report errors

## SYNOPSIS

\#include \<libexplain/vsnprintf.h\>

int explain\_vsnprintf\_or\_die(char \*data, size\_t data\_size, const char \*format, va\_list ap);\
 int explain\_vsnprintf\_on\_error(char \*data, size\_t data\_size, const char \*format, va\_list ap);

## DESCRIPTION

The **explain\_vsnprintf\_or\_die** function is used to call the [*vsnprintf*(3)](/vsnprintf/3.md) system call. On failure an explanation will be printed to *stderr*, obtained from the [*explain\_vsnprintf*(3)](/explain_vsnprintf/3.md) function, and then the process terminates by calling `exit(EXIT_FAILURE)`.

The **explain\_vsnprintf\_on\_error** function is used to call the [*vsnprintf*(3)](/vsnprintf/3.md) system call. On failure an explanation will be printed to *stderr*, obtained from the [*explain\_vsnprintf*(3)](/explain_vsnprintf/3.md) function, but still returns to the caller.

- *data*

  The data, exactly as to be passed to the [*vsnprintf*(3)](/vsnprintf/3.md) system call.

- *data\_size*

  The data\_size, exactly as to be passed to the [*vsnprintf*(3)](/vsnprintf/3.md) system call.

- *format*

  The format, exactly as to be passed to the [*vsnprintf*(3)](/vsnprintf/3.md) system call.

- *ap*

  The ap, exactly as to be passed to the [*vsnprintf*(3)](/vsnprintf/3.md) system call.

## RETURN VALUE

The **explain\_vsnprintf\_or\_die** function only returns on success, see [*vsnprintf*(3)](/vsnprintf/3.md) for more information. On failure, prints an explanation and exits, it does not return.

The **explain\_vsnprintf\_on\_error** function always returns the value return by the wrapped [*vsnprintf*(3)](/vsnprintf/3.md) system call.

## EXAMPLE

The **explain\_vsnprintf\_or\_die** function is intended to be used in a fashion similar to the following example:

```
int result = explain_vsnprintf_or_die(data, data_size, format, ap);
```

## SEE ALSO

- [*vsnprintf*(3)](/vsnprintf/3.md)

  formatted output conversion

- [*explain\_vsnprintf*(3)](/explain_vsnprintf/3.md)

  explain [*vsnprintf*(3)](/vsnprintf/3.md) errors

- [*exit*(2)](/exit/2.md)

  terminate the calling process

## COPYRIGHT

libexplain version 1.4\
 Copyright (C) 2010 Peter Miller