RFC: blank() Function as a Complement to empty()

Hi Kayck,

Thanks for your proposal. Here are some points from me:

empty() is not a function, it's a language construct that's a shorthand for
!isset($var) || $var == false.

While it has its uses empty() should be avoided whenever possible. It's
generally a sign of the programmer being lazy not doing proper data
validation/type checking.

The zero-string being considered falsey isn't limited to empty(). It's just
how PHP types work. Introducing a new function with slightly different
semantics would create tons of confusion. On top of that, your new function
proposes rules that are unintuitive and very likely applicable only to your
project. Getting everyone to agree to these rules would be near impossible.

You can very easily create this function in global scope in your project
but introducing this at the language level would potentially break a lot of
existing code. It's not inconceivable that people have defined such a
function in global scope in their projects already.

My stance is that I am categorically against it even if the semantics would
have been more ironed out. Unless PHP is about to phase out loose
comparison, we don't need a new function that is just an opinionated
variation of it.

Thank you for the proposal and please don't be disheartened by my strong
opinion.

Regards,
Kamil

INTRODUCTION
This RFC proposes the addition of a new global function blank() to PHP’s
core, intended to provide a more intuitive and context-sensitive way of
checking for "blank" values. This function is not a replacement for
empty(), but a *complementary tool *to help developers more accurately
evaluate user input, query parameters, and form values — particularly in
situations where empty() may behave in unintuitive ways.

MOTIVATIONThe motivation for this RFC arose from a real-world issue I
encountered at work involving query string filtering — specifically when
using the string "0" as a filter value. Because empty("0") evaluates to
true, the logic skipped this valid input, causing incorrect behavior in
the application. This highlighted a gap in PHP’s current toolset for
handling “blank” values in a more semantic and intention-aligned way.

PROPOSAL
The proposed blank() function will behave similarly to empty(), but with
semantics better suited for filtering, validation, and user input. Its
primary goals are:

To treat whitespace-only strings as blank (e.g., " ").

To treat "0" (string zero) and 0 (int zero) as not blank, unlike
empty().

To support clearer, intention-driven logic when working with dynamic
input, especially in query strings and HTTP forms.

Function Signature

function blank(mixed $value): bool;

Logic (PHP version)

function blank(mixed $value): bool
{
if (
false === $value ||
(empty($value) && '0' != $value) ||
(\is_string($value) && '' === \trim($value))
) {
return true;
}

return false;

}

Examples
echo blank(null); // true
echo blank(false); // true
echo blank(""); // true
echo blank(" "); // true
echo blank([]); // true

echo blank(0); // false
echo blank("0"); // false
echo blank("test"); // false
echo blank([0]); // false

BACKWARDS INCOMPATIBLE CHANGES
This feature is fully backward-compatible. It does not alter existing
behavior of any function or construct, nor does it redefine empty(). It
introduces a new global function and does not break any existing code.

RFC IMPACT

CLI & Web usage: This function will be available globally, in both
CLI and Web SAPI contexts.

Core behavior: The function is small, simple, and does not interfere
with any existing language behavior or constructs.

php.ini: No changes required.

New constants: None introduced.

This function is expected to improve code clarity and correctness in
real-world applications, without burdening the language with complexity.

COMMUNITY FEEDBACKMultiple developers have voiced concerns regarding
empty() in real-world scenarios. A key example is PHP Issue #9845
https://github.com/php/php-src/issues/9845 on GitHub, where it's
reported that:

"empty("0") returns true when it should return false."

This discussion highlights a recurring problem: developers often expect
'0' to be treated as a valid, non-empty input (e.g., in filtering query
strings), but empty() evaluates it as false. This leads to conditional
logic silently skipping valid inputs.

The blank() function is designed to directly address this gap, offering a
more semantic and human-friendly approach to "blankness" that aligns better
with what developers actually expect in these cases.

NEXT STEPSThis is my first RFC proposal, If there are any issues with
the approach, naming, scope, or anything I may have overlooked, I’d greatly
appreciate your guidance.

If there’s interest in moving forward, I will prepare the full RFC
documentation on the wiki along with an implementation patch and
appropriate tests.

Thanks in advance for your time and input!

Best Regards,
Kayck Matias ☕

INTRODUCTION
This RFC proposes the addition of a new global function blank() to PHP’s core, intended to provide a more intuitive and context-sensitive way of checking for "blank" values. This function is not a replacement for empty(), but a *complementary tool *to help developers more accurately evaluate user input, query parameters, and form values — particularly in situations where empty() may behave in unintuitive ways.

*MOTIVATION
*The motivation for this RFC arose from a real-world issue I encountered at work involving query string filtering — specifically when using the string "0" as a filter value. Because empty("0") evaluates to true, the logic skipped this valid input, causing incorrect behavior in the application. This highlighted a gap in PHP’s current toolset for handling “blank” values in a more semantic and intention-aligned way.

I would personally advocate that empty() NEVER be used on strings. There are too many edge cases. As I said in an earlier message on the thread, if you want to know if a string is empty, just do $string == "" -- note the double equals, not triple equals. This matches null, an actual empty string, and false, but won't match anything else.

PROPOSAL
The proposed blank() function will behave similarly to empty(), but with semantics better suited for filtering, validation, and user input. Its primary goals are:
• To treat whitespace-only strings as blank (e.g., " ").

• To treat "0" (string zero) and 0 (int zero) as not blank, unlike empty().

• To support clearer, intention-driven logic when working with dynamic input, especially in query strings and HTTP forms.

Function Signature

function blank(mixed $value): bool;
**
Logic (PHP version)
function blank(mixed $value): bool
{
if (
false === $value ||
(empty($value) && '0' != $value) ||
(\is_string($value) && '' === \trim($value))
) {
return true;
}

return false;

}
Examples
echo blank(null); // true
echo blank(false); // true
echo blank(""); // true
echo blank(" "); // true
echo blank([]); // true

echo blank(0); // false
echo blank("0"); // false
echo blank("test"); // false
echo blank([0]); // false

I agree with most of these. I do not agree that " " (a space) is blank though. For people without last names, this is often their last name to pass validation on forms. As I said earlier, a simple loose check with an empty string is usually all you need, not empty().

Best Regards,
Kayck Matias ☕

— Rob