# PR_STATIC_ASSERT

Prevents code from compiling when an expression has the value `FALSE`
at compile time.

## Syntax

```{code}
#include <prlog.h>

PR_STATIC_ASSERT ( expression );
```

### Parameters

The macro has this parameter:

expression

: Any valid expression which evaluates at compile-time to `TRUE` or
  `FALSE`. An expression which cannot be evaluated at compile time
  will cause a compiler error; see {ref}`PR_ASSERT` for a runtime
  alternative.

### Returns

Nothing

## Description

This macro evaluates the specified expression. When the result is zero
(`FALSE`) program compilation will fail with a compiler error;
otherwise compilation completes successfully. The compiler error will
include the number of the line for which the compile-time assertion
failed.

This macro may only be used in locations where an `extern` function
declaration may be used.