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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: 27-May-2019 14:14 GMT

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

Syntax

 = floatval();

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.

(var parameter)

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

Examples

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

String Conversion

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

Number Conversion

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

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

Array Conversion

 = floatval();
statement
array() = floatval(array());0
array("x", "y", "z") = 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:

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

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