Checking for number of characters

[Chris_Evans]

Hi - is there anyway I can use the following if statement to check for the number of characters and to check that the characters only contain letters such as ABC and not letters such as &?

The if statement is currently as follows:

			if($_POST['spnumber'] == '' or !$_POST['spnumber'])
				{
				echo 'Please be sure to enter an SP Number.<br>';
				}

Thanks in advance,

Chris

[laserlight]

use strlen() to check the number of characters, and ctype_alnum() to ensure alphanumeric characters

[Chris_Evans]

Thanks for that... found this piece of code in the function list on php.net.

<? 
$s="blah0blah";
$si=0;
$s_len=strlen($s);
for ($si=0;$si<$s_len;$si++)
{
$c=$s[$si];

echo $si;
}
?>

Presumably what thats doing is using $s as the text, $si as the starting number, $s_len to count the string length and then using the for statement to check that it's not less that zero.

Changing the code to this allows for correct counting... however it writes the number of letters for each letter.... is there anyway I can use this in the code?

<? 
$s="blah0blah";
$si=0;
$s_len=strlen($s);
for ($si=0;$si<$s_len;$si++)
{
$c=$s[$si];

echo $s_len;
}
?>

Since the result returned is 999999999 which is the correct number but that wouldn't work in code unless you used echo $si which counts up to the last letter - 012345678 - I can't think of a way of using it in code.

Thanks in advance,

Chris

[laserlight]

what do you want to do now?

[Chris_Evans]

Bit of a long post a wrote above lol... well what I tried to say above was that I can't find a way of putting it into an if statement.

It checks correctly but returns the result of either 012345678 or 999999999 which means that when it checks to see if the field contains only 9 characters it returns the result of yes if it has 50 i think. 😐

Thanks,

Chris

[laserlight]

A simple solution would be:

function checkField($value, $len) {
	//check if length is correct
	if (strlen($value) == $len) {
		//check if value is alphanumeric
		if (ctype_alnum($value)) {
			return true;
		}
		else {
			return false;
		}
	}
	else {
		return false;
	}
}

[Chris_Evans]

When you have a function, do you have to call it to get it to work?

I'm only just starting on functions.

::::

			if($_POST['spnumber'] == '' or !$_POST['spnumber'])
				{
				echo 'Please be sure to enter an SP Number.<br>';
				}
			else
				{
					$spnumber = $_POST['spnumber'];
					$len = '2';
					function checkField($spnumber, $len) { 
						//check if length is correct 
						if (strlen($spnumer) == $len) { 
							//check if value is alphanumeric 
							if (ctype_alnum($spnumber)) { 
								return true; 
							} 
							else { 
								echo 'Please make sure the SP Number only contains alphanumberic numbers. ABC/123.';
								return false; 
							} 
						} 
						else { 
							echo 'Please make sure the SP Number is nine characters or less.';
							return false; 
						} 
					}
				}

It's supposed to echo now when the spnumber is more than 2, correct?

But I presume you need to call it as I seem to remember hearing about calling functions before.

If so, how can you?

Thanks,

Chris

[laserlight]

The answer is probably more like:

<?php
function checkField($spnumber, $len) {
	//check if length is correct
	if (strlen($spnumer) == $len) {
		//check if value is alphanumeric
		if (ctype_alnum($spnumber)) {
			return true;
		}
		else {
			echo 'Please make sure the SP Number only contains alphanumberic numbers. ABC/123.';
			return false;
		}
	}
	else {
		echo 'Please make sure the SP Number is nine characters or less.';
		return false;
	}
}


if (empty($_POST['spnumber']))
{
	echo 'Please be sure to enter an SP Number.<br>';
}
else
{
	$spnumber = $_POST['spnumber'];
	if (checkField($spnumber)) {
		//do what you need to do with spnumber
	}
}
?>

[Chris_Evans]

🙂