Check jika string hanya mengandung angka PHP

ctype_digit()

Cara termudah dan tercepat untuk mengecek seluruh karakter string adalah nomor ialah dengan menggunakan ctype_digit ( )

$var = '1337';

if(ctype_digit($var)){
   echo 'This string contains only digits';
} 

preg_match()

Cara lain untuk mengecek apakah kalimat tersebut hanya mengandung angka adalah dengan menggunaakan preg_match(). preg_match() akan mencari suatu pola dan mengembalikan jumlah pola yang sesuai. Dalam contoh berikut akan digunakan 3 macam pola yang sebetulya memiliki makna yang sama. String harus mengandung hanya angka.

if(preg_match('/^\d+$/',$var)){
   echo 'This string contains only digits';
} 

if(preg_match("/^[0-9]+$/",$var)){
   echo 'This string contains only digits';
} 

if(preg_match("/^[[:digit:]]+$/",$var)){
   echo 'This string contains only digits';
}

[0-9] dan [:digit:] adalah character classes that means we are only looking for numbers in the string. In other words,[0-9] is a pattern that covers all digits:0 1 2 3 4 5 6 7 8 9. \d is a shorthand of [0-9] and [:digit:].

Jangan gunakan is_numeric() atau is_int()

is_numeric() and is_int() are not really meant to check if a string contains only numbers.

is_numeric() will return TRUE if a string is a numeric string but don't forget a numeric string is not necessarily an integer. A numeric string can also be a decimal number or a negative number. That is why you would not want to use is_numeric() if you are only looking for positive integers (0 1 2 3 4 5 6 7 8 9).

$tests = array('1.3', '-2', '1e3');

foreach($tests as $element){
 if(is_numeric($element)) {
  echo $element.' is numeric
';
 }
}

This script will output:

1.3 is numeric
1e3 is numeric
-2 is numeric

is_int() will return TRUE if the type of a variable is integer. That means it will return TRUE for integers that are positive or negative numbers.

if(is_int(-1)) {
 echo 'This number is an integer';
}

is_int() checks the type of a variable (a variable can be a boolean, an integer, a string, an array or plenty other things). As you may want to check if the values sent through a form contains only numbers, don't forget that everything from $_POST is considered as a string. So doing something like is_int($_POST['var']) will always return FALSE, even if this string contains numbers only.

$var = '3';

if(!is_int($var)){
 echo '$var is a '.gettype($var).', it is not an integer';
}

This script will output:

3 is a string, it is not an integer