Sara
Sara

Reputation: 14638

How do I convert a string to a number in PHP?

I want to convert these types of values, '3', '2.34', '0.234343', etc. to a number. In JavaScript we can use Number(), but is there any similar method available in PHP?

Input             Output
'2'               2
'2.34'            2.34
'0.3454545'       0.3454545

Upvotes: 963

Views: 3068179

Answers (30)

ComputerGuy
ComputerGuy

Reputation: 79

Update for PHP 8:

There is a function called intval() that allows you to convert a string to a number. You can read more on https://www.php.net/manual/en/function.intval.php

For example:

intval("376") would output 376

or

intval(376) would output 376

Upvotes: 2

ksenija
ksenija

Reputation: 33

You can just add 0 to your string, and you will convert it to number without losing initial original value. Try for example:

dd('0.3454545' + 0)

PHP will handle conversion for you, or as already suggested add + before your string.

Upvotes: 0

F.K. Juliano
F.K. Juliano

Reputation: 83

Use the unary operator (+). For instance:

$n1 = +'7';
$n2 = '2.34';
$n2 = +$n1;

var_dump($n1): int(7) var_dump($n2): float(2.34)

Upvotes: 1

Hef
Hef

Reputation: 1460

function convert_to_number($number) {
    return is_numeric($number) ? ($number + 0) : FALSE;
}

Upvotes: 4

MikelG
MikelG

Reputation: 489

Alright so I just ran into this issue. My problem is that the numbers/strings in question having varying numbers of digits. Some have no decimals, others have several. So for me, using int, float, double, intval, or floatval all gave me different results depending on the number.

So, simple solution... divide the string by 1 server-side. This forces it to a number and retains all digits while trimming unnecessary 0's. It's not pretty, but it works.

"your number string" / 1

Input       Output
"17"        17
"84.874"    84.874
".00234"    .00234
".123000"   .123
"032"       32

Upvotes: 11

Andy
Andy

Reputation: 5091

Now we are in an era where strict/strong typing has a greater sense of importance in PHP, I use json_decode:

$num = json_decode('123');

var_dump($num); // outputs int(123)

$num = json_decode('123.45');

var_dump($num); // outputs float(123.45)

Upvotes: 7

klodoma
klodoma

Reputation: 4599

If you want the numerical value of a string and you don't want to convert it to float/int because you're not sure, this trick will convert it to the proper type:

function get_numeric($val) {
  if (is_numeric($val)) {
    return $val + 0;
  }
  return 0;
}

Example:
<?php
get_numeric('3'); // int(3)
get_numeric('1.2'); // float(1.2)
get_numeric('3.0'); // float(3)
?>

Source: https://www.php.net/manual/en/function.is-numeric.php#107326

Upvotes: 14

hackernewbie
hackernewbie

Reputation: 1722

One of the many ways it can be achieved is this:

$fileDownloadCount          =  (int) column_data_from_db;
$fileDownloadCount++;

The second line increments the value by 1.

Upvotes: 2

Benni
Benni

Reputation: 1033

Late to the party, but here is another approach:

function cast_to_number($input) {
    if(is_float($input) || is_int($input)) {
        return $input;
    }
    if(!is_string($input)) {
        return false;
    }
    if(preg_match('/^-?\d+$/', $input)) {
        return intval($input);
    }
    if(preg_match('/^-?\d+\.\d+$/', $input)) {
        return floatval($input);
    }
    return false;
}

cast_to_number('123.45');       // (float) 123.45
cast_to_number('-123.45');      // (float) -123.45
cast_to_number('123');          // (int) 123
cast_to_number('-123');         // (int) -123
cast_to_number('foo 123 bar');  // false

Upvotes: 5

Zahid Gani
Zahid Gani

Reputation: 165

//Get Only number from string
$string = "123 Hello Zahid";
$res = preg_replace("/[^0-9]/", "", $string);
echo $res."<br>";
//Result 123

Upvotes: 1

user1657853
user1657853

Reputation: 160

If you don't know in advance if you have a float or an integer,
and if the string may contain special characters (like space, €, etc),
and if it may contain more than 1 dot or comma,
you may use this function:

// This function strip spaces and other characters from a string and return a number.
// It works for integer and float.
// It expect decimal delimiter to be either a '.' or ','
// Note: everything after an eventual 2nd decimal delimiter will be removed.
function stringToNumber($string) {
    // return 0 if the string contains no number at all or is not a string:
    if (!is_string($string) || !preg_match('/\d/', $string)) {
        return 0;
    } 

    // Replace all ',' with '.':
    $workingString = str_replace(',', '.', $string);

    // Keep only number and '.':
    $workingString = preg_replace("/[^0-9.]+/", "", $workingString);

    // Split the integer part and the decimal part,
    // (and eventually a third part if there are more 
    //     than 1 decimal delimiter in the string):
    $explodedString = explode('.', $workingString, 3);

    if ($explodedString[0] === '') {
        // No number was present before the first decimal delimiter, 
        // so we assume it was meant to be a 0:
        $explodedString[0] = '0';
    } 

    if (sizeof($explodedString) === 1) {
        // No decimal delimiter was present in the string,
        // create a string representing an integer:
        $workingString = $explodedString[0];
    } else {
        // A decimal delimiter was present,
        // create a string representing a float:
        $workingString = $explodedString[0] . '.' .  $explodedString[1];
    }

    // Create a number from this now non-ambiguous string:
    $number = $workingString * 1;

    return $number;
}

Upvotes: 2

rolodef
rolodef

Reputation: 115

Only multiply the number by 1 so that the string is converted to type number.

//String value
$string = "5.1"
if(is_numeric($string)){
  $numeric_string = $string*1;
}

Upvotes: 7

Dragas
Dragas

Reputation: 1323

I've been reading through answers and didn't see anybody mention the biggest caveat in PHP's number conversion.

The most upvoted answer suggests doing the following:

$str = "3.14"
$intstr = (int)$str // now it's a number equal to 3

That's brilliant. PHP does direct casting. But what if we did the following?

$str = "3.14is_trash"
$intstr = (int)$str

Does PHP consider such conversions valid?

Apparently yes.

PHP reads the string until it finds first non-numerical character for the required type. Meaning that for integers, numerical characters are [0-9]. As a result, it reads 3, since it's in [0-9] character range, it continues reading. Reads . and stops there since it's not in [0-9] range.

Same would happen if you were to cast to float or double. PHP would read 3, then ., then 1, then 4, and would stop at i since it's not valid float numeric character.

As a result, "million" >= 1000000 evaluates to false, but "1000000million" >= 1000000 evaluates to true.

See also:

https://www.php.net/manual/en/language.operators.comparison.php how conversions are done while comparing

https://www.php.net/manual/en/language.types.string.php#language.types.string.conversion how strings are converted to respective numbers

Upvotes: 12

Anuga
Anuga

Reputation: 2827

There is a way:

$value = json_decode(json_encode($value, JSON_NUMERIC_CHECK|JSON_PRESERVE_ZERO_FRACTION|JSON_UNESCAPED_SLASHES), true);

Using is_* won't work, since the variable is a: string.

Using the combination of json_encode() and then json_decode() it's converted to it's "true" form. If it's a true string then it would output wrong.

$num = "Me";
$int = (int)$num;
$float = (float)$num;

var_dump($num, $int, $float);

Will output: string(2) "Me" int(0) float(0)

Upvotes: 3

aldemarcalazans
aldemarcalazans

Reputation: 1534

Yes, there is a similar method in PHP, but it is so little known that you will rarely hear about it. It is an arithmetic operator called "identity", as described here:

Aritmetic Operators

To convert a numeric string to a number, do as follows:

$a = +$a;

Upvotes: 42

Aleksei Akireikin
Aleksei Akireikin

Reputation: 1997

If you want get a float for $value = '0.4', but int for $value = '4', you can write:

$number = ($value == (int) $value) ? (int) $value : (float) $value;

It is little bit dirty, but it works.

Upvotes: 29

Rocco Galasso
Rocco Galasso

Reputation: 19

All suggestions lose the numeric type.

This seems to me a best practice:

function str2num($s){
// Returns a num or FALSE
    $return_value =  !is_numeric($s) ? false :               (intval($s)==floatval($s)) ? intval($s) :floatval($s);
    print "\nret=$return_value type=".gettype($return_value)."\n";
}

Upvotes: 1

webNeat
webNeat

Reputation: 2828

Instead of having to choose whether to convert the string to int or float, you can simply add a 0 to it, and PHP will automatically convert the result to a numeric type.

// Being sure the string is actually a number
if (is_numeric($string))
    $number = $string + 0;
else // Let the number be 0 if the string is not a number
    $number = 0;

Upvotes: 44

drugan
drugan

Reputation: 829

In addition to Boykodev's answer I suggest this:

Input             Output
'2' * 1           2 (int)
'2.34' * 1        2.34 (float)
'0.3454545' * 1   0.3454545 (float)

Upvotes: 8

Adrian Cornish
Adrian Cornish

Reputation: 23906

PHP will do it for you within limits

<?php
   $str = "3.148";
   $num = $str;

   printf("%f\n", $num);
?>

Upvotes: 0

Dominic Amal Joe F
Dominic Amal Joe F

Reputation: 337

Simply you can write like this:

<?php
    $data = ["1","2","3","4","5"];
    echo json_encode($data, JSON_NUMERIC_CHECK);
?>

Upvotes: 3

Brendan
Brendan

Reputation: 472

I got the question "say you were writing the built in function for casting an integer to a string in PHP, how would you write that function" in a programming interview. Here's a solution.

$nums = ["0","1","2","3","4","5","6","7","8","9"];
$int = 15939; 
$string = ""; 
while ($int) { 
    $string .= $nums[$int % 10]; 
    $int = (int)($int / 10); 
} 
$result = strrev($string);

Upvotes: -2

gopeca
gopeca

Reputation: 1715

To avoid problems try intval($var). Some examples:

<?php
echo intval(42);                      // 42
echo intval(4.2);                     // 4
echo intval('42');                    // 42
echo intval('+42');                   // 42
echo intval('-42');                   // -42
echo intval(042);                     // 34 (octal as starts with zero)
echo intval('042');                   // 42
echo intval(1e10);                    // 1410065408
echo intval('1e10');                  // 1
echo intval(0x1A);                    // 26 (hex as starts with 0x)
echo intval(42000000);                // 42000000
echo intval(420000000000000000000);   // 0
echo intval('420000000000000000000'); // 2147483647
echo intval(42, 8);                   // 42
echo intval('42', 8);                 // 34
echo intval(array());                 // 0
echo intval(array('foo', 'bar'));     // 1
?>

Upvotes: 99

Boykodev
Boykodev

Reputation: 930

You can always add zero to it!

Input             Output
'2' + 0           2 (int)
'2.34' + 0        2.34 (float)
'0.3454545' + 0   0.3454545 (float)

Upvotes: 22

CogSciGradStudent
CogSciGradStudent

Reputation: 141

Here is the function that achieves what you are looking for. First we check if the value can be understood as a number, if so we turn it into an int and a float. If the int and float are the same (e.g., 5 == 5.0) then we return the int value. If the int and float are not the same (e.g., 5 != 5.3) then we assume you need the precision of the float and return that value. If the value isn't numeric we throw a warning and return null.

function toNumber($val) {
    if (is_numeric($val)) {
        $int = (int)$val;
        $float = (float)$val;

        $val = ($int == $float) ? $int : $float;
        return $val;
    } else {
        trigger_error("Cannot cast $val to a number", E_USER_WARNING);
        return null;
    }
}

Upvotes: 12

Dieter Gribnitz
Dieter Gribnitz

Reputation: 5218

Here is a function I wrote to simplify things for myself:

It also returns shorthand versions of boolean, integer, double and real.

function type($mixed, $parseNumeric = false)
{        
    if ($parseNumeric && is_numeric($mixed)) {
        //Set type to relevant numeric format
        $mixed += 0;
    }
    $t = gettype($mixed);
    switch($t) {
        case 'boolean': return 'bool'; //shorthand
        case 'integer': return 'int';  //shorthand
        case 'double': case 'real': return 'float'; //equivalent for all intents and purposes
        default: return $t;
    }
}

Calling type with parseNumeric set to true will convert numeric strings before checking type.

Thus:

type("5", true) will return int

type("3.7", true) will return float

type("500") will return string

Just be careful since this is a kind of false checking method and your actual variable will still be a string. You will need to convert the actual variable to the correct type if needed. I just needed it to check if the database should load an item id or alias, thus not having any unexpected effects since it will be parsed as string at run time anyway.

Edit

If you would like to detect if objects are functions add this case to the switch:

case 'object': return is_callable($mixed)?'function':'object';

Upvotes: 6

fardjad
fardjad

Reputation: 20424

There are a few ways to do so:

  1. Cast the strings to numeric primitive data types:

    $num = (int) "10";
    $num = (double) "10.12"; // same as (float) "10.12";
    
  2. Perform math operations on the strings:

    $num = "10" + 1;
    $num = floor("10.1");
    
  3. Use intval() or floatval():

    $num = intval("10");
    $num = floatval("10.1");
    
  4. Use settype().

Upvotes: 279

vernonner3voltazim
vernonner3voltazim

Reputation: 786

I've found that in JavaScript a simple way to convert a string to a number is to multiply it by 1. It resolves the concatenation problem, because the "+" symbol has multiple uses in JavaScript, while the "*" symbol is purely for mathematical multiplication.

Based on what I've seen here regarding PHP automatically being willing to interpret a digit-containing string as a number (and the comments about adding, since in PHP the "+" is purely for mathematical addition), this multiply trick works just fine for PHP, also.

I have tested it, and it does work... Although depending on how you acquired the string, you might want to apply the trim() function to it, before multiplying by 1.

Upvotes: 5

Mehdi Ajdari
Mehdi Ajdari

Reputation: 75

You can use:

((int) $var)   ( but in big number it return 2147483647 :-) )

But the best solution is to use:

if (is_numeric($var))
    $var = (isset($var)) ? $var : 0;
else
    $var = 0;

Or

if (is_numeric($var))
    $var = (trim($var) == '') ? 0 : $var;
else
    $var = 0;

Upvotes: 3

Your Common Sense
Your Common Sense

Reputation: 157981

In whatever (loosely-typed) language you can always cast a string to a number by adding a zero to it.

However, there is very little sense in this as PHP will do it automatically at the time of using this variable, and it will be cast to a string anyway at the time of output.

Note that you may wish to keep dotted numbers as strings, because after casting to float it may be changed unpredictably, due to float numbers' nature.

Upvotes: 50

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