ctype_digit to validate numeric characters in PHP

$var='37'; // All are numeric chars
//$var=37; //  All or some are not numeric chars
//$var='2b45'; // All or some are not numeric chars
//$var='abcd'; // All or some are not numeric chars

if(ctype_digit($var)){
	echo "<b>$var</b> All are numeric chars ";
}else{ 
	echo " <b>$var</b> All or some are not numeric chars";
}

Output

37 All are numeric chars

Syntax

bool ctype_digit ( string $input_string )

$input_string : String to be checked.

ctype_digit() is a PHP filter function checks if all chars in the $input_string are numeric or not. Any thing other than this if present then it return FALSE.

This is a good function to check data coming from insecure sources like user input data. Before storing or processing such data we can use this function check to match our requirement.

Now let us try with some examples.

echo ctype_digit('37'); // Output is 1 
echo "<br>";
echo ctype_digit(37); 
echo "<br>";
echo ctype_digit('2b45');
echo "<br>";
echo ctype_digit('abcd');
echo "<HR>";

ctype_digit(37); output is False as it is taken as ASCII 37, which is %

Example 2

$str = array('434.34', '4003', 'ab!34',67);
foreach ($str as $val) {
if (ctype_digit($val)) {
 echo "<p class='text-success'>The string $val consists of all digits.</p><br>";
} else {
 echo "<p class='text-danger'>The string $val does not consist of one Or  all digits.</p><br>";
 }
}

Output is here

The string 434.34 does not consist of one Or  all digits.
The string 4003 consists of all digits.
The string ab!34 does not consist of one Or  all digits.
The string 67 does not consist of one Or  all digits.

You can change the value of the variable $var and see the result. Decimal points are not allowed ( False ) in ctype_digit.

For easy understanding here is the form to submit data to above script

Output of HTML forms.

Output of all html forms are in string format. Hence if you enter number 35 in the above text box , it will be considered as a string 35 and hence output is equal to True. But if you check the below code the output will be equal to False as it will be considered as ASCII 35 which is equal to #.

echo ctype_digit(35);

Check for only alphabetic characters by ctype_alpha() Check for all lower or upper Check for at least one lower case or upper case
ctype()

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ctype_digit(): to check numeric characters

Example 2

Output of HTML forms.

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