Php/docs/migration51.integer-parameters
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Integer values in function parameters
With the advent of PHP 5.0.x, a new parameter parsing API was introduced
which is used by a large number of PHP functions. In all versions of PHP
between 5.0.x and 5.1.x, the handling of integer values was very strict and
would reject non-well formed numeric values when a PHP function expected an
integer. These checks have now been relaxed to support non-well formed
numeric strings such as " 123" and "123 ", and will no longer fail as they
did under PHP 5.0.x. However, to promote code safety and input validation,
PHP functions will now emit an E_NOTICE when such
strings are passed as integers.
