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PHP: Converting A String To Float Value

Document Reference: TN200906004 - Rev: 4.7 - Last Update: 28-06-2016 07:48 GMT - Downloaded: 25-Jun-2024 18:13 GMT

The floatval() variable handling function can be used to convert a string to a floating point number (aka float, double, or real number).


$float = floatval($any_variable);


The returned float value on successful conversion, or 0 on failure. Empty arrays will return 0 and non-empty arrays will return 1. See examples below.

$any_variable (var parameter)

Required parameter that accepts multiple data types. It is a scalar value being converted to an integer.


Code snippets in examples below have been tested in PHP parser version 5.5.36.

String Conversion

$float = floatval($any_variable);
"37.5"$float = floatval("37.5");37.5
"37.0"$float = floatval("37.0");37
"37"$float = floatval("37");37
"37e3"$float = floatval("37e3");3700
"37E3"$float = floatval("37E3");3700
"37e-3"$float = floatval("37e-3");0.0037
"37E-3"$float = floatval("37E-3");0.0037
"+37"$float = floatval("+37");37
"-37"$float = floatval("-37");-37
"0b100101"$float = floatval("0b100101");0
"037"$float = floatval("037");37
"0x25"$float = floatval("0x25");0
"37 coins"$float = floatval("37 coins");37
"37%"$float = floatval("37%");37
"37C"$float = floatval("37C");37
"X37"$float = floatval("X37");0

Number Conversion

$float = floatval($any_variable);
37.5$float = floatval(37.5);37.5
37.0$float = floatval(37.0);37
37$float = floatval(37);37
37e3$float = floatval(37e3);3700
37E3$float = floatval(37E3);3700
37e-3$float = floatval(37e-3);0.0037
37E-3$float = floatval(37E-3);0.0037
+37$float = floatval(+37);37
-37$float = floatval(-37);-37
0b100101$float = floatval(0b100101);37 1)
037$float = floatval(037);55 2)
045$float = floatval(045);37 2)
0x37$float = floatval(0x37);55 3)
0x25$float = floatval(0x25);37 3)

1) Value for $any_variable precedes with 0b indicating binary (base 2) notation (available since PHP parser version 5.4.0).
2) Value for $any_variable precedes with 0 indicating octal (base 8) notation.
3) Value for $any_variable precedes with 0x indicating hexadecimal (base 16) notation.

Array Conversion

$float = floatval($any_variable);
array()$float = floatval(array());0
array("x", "y", "z")$float = floatval(array("x", "y", "z"));1

Rounding Precision

Some decimal numbers, such as 0.1 or 0.7, do not have an exact representation as a binary number and can not be converted to their binary counterparts without a small loss of precision. Hence, some rounding errors must be expected when coding. E.g., try this:

 $string1 = "9 m";
$string2 = "6.9 m";
if (floatval($string1) - floatval($string2) == 2.1) {
  echo floatval($string1)." - ".floatval($string2)." = 2.1";
else {
echo floatval($string1)." - ".floatval($string2)." ≠ 2.1";

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