What is the easiest way to check if a string contains a valid float?
For example
is_string_float("1") = true
is_string_float("1.234") = true
is_string_float("1.2e3") = true
is_string_float("1b2") = false
is_string_float("aldhjsfb") = false
4 Answers
If you really want to know if a string contains a float and ONLY a float you cannot use is_float() (wrong type) or is_numeric() (returns true for a string like "1" too) only. I'd use
<?php
function foo(string $string) : bool {
return is_numeric($string) && strpos($string, '.') !== false;
}
?>
instead.
1 Comment
alexkb
is_float() is checking the type not whether the value can be coerced to a float - which is what something like is_numeric() does but for integers.The easiest way would be to use built in function is_float(). To test if a variable is a number or a numeric string you must use is_numeric().
1 Comment
marcosh
is_numeric is what I was looking formaybe you can use a couple of functions
out of the box
function is_string_float($string) {
if(is_numeric($string)) {
$val = $string+0;
return is_float($val);
}
return false;
}
3 Comments
Harry
This will error in PHP8 as addition cannot be performed on a string and an int.
georaldc
@Harry I'm pretty sure the is_numeric check would ensure that PHP treats the string as an int (or float) before the addition operation is done.
avpaderno
PHP 8.2 complains only with code similar to
echo "Z" + 0, "\n";. echo "1" + 0, "\n"; will print 1 without throwing any exception.This can easily be achieved by double casting.
/**
* @param string $text
* @return bool
*/
function is_string_float(string $text): bool
{
return $text === (string) (float) $text;
}
1 Comment
Sundae
Unfortunately, this does not work on a string like "0.000"
is_float("1") = false1in an integer"1"is a string, not a float. The same holds foris_float("1.234")