Is there a difference between is_int() and ctype_digit()?

Question

is_int() returns true if the argument is an integer type, ctype_digit() takes a string argument and returns true if all the characters in the string are digits.

Example:

┌──────────┬───────────┬────────────────┐
│          │  is_int:  │  ctype_digit:  │
├──────────┼───────────┼────────────────┤
│ 123      │  true     │  false         │
├──────────┼───────────┼────────────────┤
│ 12.3     │  false    │  false         │
├──────────┼───────────┼────────────────┤
│ "123"    │  false    │  true          │
├──────────┼───────────┼────────────────┤
│ "12.3"   │  false    │  false         │
├──────────┼───────────┼────────────────┤
│ "-1"     │  false    │  false         │
├──────────┼───────────┼────────────────┤
│ -1       │  true     │  false         │
└──────────┴───────────┴────────────────┘

There is also is_numeric which returns true if passed in value can be parsed as number.

If I try to compare performance of functions on PHP 5.5.30 here are the results:

This is the code I used for benchmark

// print table cell and highlight if lowest value is used
function wr($time1, $time2, $time3, $i) {
    if($i == 1) $time = $time1;
    if($i == 2) $time = $time2;
    if($i == 3) $time = $time3;

    echo('<td>');
    if(min($time1, $time2, $time3) === $time) printf('<b>%.4f</b>', $time);
    else printf('%.4f', $time);
    echo('</td>');
}


$test_cases = array( 123, 12.3, '123', true);
$tests = 1000000;
$result = true;  // Used just to make sure cycles won't get optimized out
echo('<table>'.PHP_EOL);
echo('<tr><td>&nbsp;</td><th>is_int</th><th>ctype_digit</th><th>is_numeric</th></tr>');
foreach($test_cases as $case) {
    echo('<tr><th>'.gettype($case).'</th>');

    $time = microtime(true);
    for($i = 0; $i < $tests; $i++) {
        $result |= is_int((int)rand());
    }
    $time1 = microtime(true)-$time;

    $time = microtime(true);
    for($i = 0; $i < $tests; $i++) {
        $result |= ctype_digit((int)rand());
    }
    $time2 = microtime(true)-$time;

    $time = microtime(true);
    for($i = 0; $i < $tests; $i++) {
        $result |= is_numeric((int)rand());
    }
    $time3 = microtime(true)-$time;

    wr($time1, $time2, $time3, 1);
    wr($time1, $time2, $time3, 2);
    wr($time1, $time2, $time3, 3);
    echo('</tr>'.PHP_EOL);
}

echo('</table>');

exit();

The last thing you should be worrying about is how fast one of these is. There is no way that checking a string for being an integer is going to be a bottleneck in your code.

ctype not always return false on integer type.

foreach(range(-1000 , 1000)as $num){
    if(ctype_digit($num)){
        echo $num . ", ";
    }    
}

ctype_digit return true for the following integer type number.

-78,-77,-71,48,49,50,51,52,53,54,55,56,57,178,179,185, 256,257,258,259,260,261,262,263,264,265,266,267,268,269,270 to 1000

the base practice is to case every number to string e.q. strval($num) or (String) $num in this case negative value (-78) will always return false.

is_int will return you true on int type value between -2147483647 to 2147483647. any value exceed that number will return you false presuming it is running on 32bits system. on 64bits it can go up to range of -9223372036854775807 to 9223372036854775807

in term of performance personally very hard to say. ctype_digit maybe faster than is_int but if you have to cast every value to string performance is reduced overall.

Well it's very interesting :) Here is all story:

is_numeric: — Finds whether a variable is a number or a numeric string, No matter value is negative or Boolean or String or any type of number, if value is purely number it will return 'true' else 'false'.

Remember: No Character Only Number any type :)

---

is_init— Find whether the type of a variable is integer, if value is purely integer then it will return 'true' else 'false'.

Remember: No Character, Double or Negative, Only Integer

---

in_integer— Alias of is_int()

---

intval:— Get the integer value of a variable, it's take all kind of value and returns only Integer value, if values are negative then returns '-Integer' value. No matter values are Integer, Float, Negative or 'NumberString' or 'NumberStringCharacter'. It's subtract the Integer values from string "If String Starts with Number".

• NumberString = A Number value in String Format
• NumberStringCharacter = A String Start with Number

Remember: You will get Integer value from Number, Float, Negative or String which is starts with Number.

---

ctype_digit— Check for numeric character(s), If a Whole Number supplied in String Format you will get 'true' else 'false'. It will work with only StringNumber, No Float, No Negative only Whole Number as String.

Remember: Whole Number as String, No Negative Number, No Float Number, No Number Type, No Character, Only Number as String.

Birds Eye View:

Thanks to http://php.net/