time_expression

NAME

time_expression - return the amount of real time that an expression
    or block took to evaluate

SYNOPSIS

int time_expression( expr );
int time_expression { statements }

DESCRIPTION

time_expression is a language construct (a compiler keyword, like
catch), not an ordinary efun.  It accepts two body styles, sharing the
same grammar as catch:

- Parenthesized expression form: `time_expression(expr)` evaluates
  <expr>.
- Block form: `time_expression { statements }` executes the statement
  block.

In both forms, the amount of real (wall-clock) time that passed during
the evaluation of the body, in microseconds, is returned as an int.
The value of the body expression itself is discarded.  The precision
of the value is not necessarily 1 microsecond; in fact, it probably is
much less precise.

It is a compile-time error to `break` or `continue` out of a
time_expression block.

EXAMPLES

```c
int usec = time_expression( users() );

int usec = time_expression {
    for (int i = 0; i < 1000; i++)
        do_something();
};
```

SEE ALSO

rusage(3), function_profile(3), time(3), catch(3)