Using the string functions

Two functions for working with infinity

is_infinite($value)
is_finite($value)

Getting an infinite value

<?php
  $inf_x = INF;            // Positive infinity, case-sensitive
  $inf_x = -INF;           // Negative infinity
  $inf_x = 1e200 * 1e200;  // Result is INF
  $inf_x = 1 + INF;        // Result is INF
  $inf_x = 1 / INF;        // Result is 0
  $inf_x = 1 / 0;          // Generates a warning
?>

Testing for an infinite value

<?php
  $result = 1e200 * 1e200;
  if (is_infinite($result)) {
    echo('Result is out of range.');
  } else {
    echo('Result is ' . $result);
  }
?>