How do I convert a string to a number in PHP?
Nadia S.
—The Problem
How do I convert a string to a number in PHP?
The Solution
We’ll take a look at four ways to convert numeric strings into numbers in PHP:
- Dynamic typing.
- The
intval()andfloatval()functions. - Type casting with
(int)and(float). - The
settype()function.
Dynamic Typing
PHP is a dynamically typed language that recognizes numerical strings. You can perform mathematical operations directly with numeric strings. When we add 5 to '3.14', we get a float of 8.14 as a result:
$string = '3.14'; $mySum = $string + 5; var_dump($mySum);
Output:
// we get a float of 8.14 float(8.14)
The intval() and floatval() Functions
intval() and floatval() FunctionsYou can pass a numeric string literal into the intval() function to get the integer version or the floatval() function to get the float version. For example:
// convert '3.9' to int and float $myFloat = floatval('3.9'); $myInt = intval('3.9'); // echo out type and value echo '$myFloat is ',var_dump($myFloat); echo '$myInt is ',var_dump($myInt);
We get an output of 3.9 as our float value. Note how casting a number to an integer won’t round it off, as'3.9' becomes 3:
$myFloat is float(3.9) $myInt is int(3)
Type Casting with (int) and (float)
(int) and (float)Make the (int) or (float) declaration in front of a numeric string literal to type cast it accordingly. For example:
$castFloat = (float) '3.9'; $castInt = (int) '3.9'; echo '$castFloat is ',var_dump($castFloat); echo '$castInt is ',var_dump($castInt);
Output:
$castFloat is float(3.9) $castInt is int(3)
The settype() Function
settype() FunctionYou can change the data type of the original numeric string into a float or integer using the settype() function. This is useful in cases where you don’t want to create a new variable to hold a value of a different data type.
In this example, we pass in the variable $pi and the datatype 'float' as arguments into the settype() function:
$pi = '3.14'; settype($pi, "float"); var_dump($pi);
The $pi value is now a float.
float(3.14)
Here we pass in 'integer' to change our $num variable to an integer:
$num = '4.5'; settype($num, 'integer'); var_dump($num);
Output:
int(4)
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