Number of letter

thenetbrainbox

I have string which contains 1 character, I need php to detect whether it is a letter or a number. How can I do this?

Thanks, Jonathon.

Threehearts

Hi!
multiply it with 1.
if its a number $input == $output
if not $output should == 0 (unless im mistaken)

oh, youll have to check $input == 0 beforehand so you can tell the difference.

greetings, jakob

thenetbrainbox

Thanks Jakob, I tried that out and it works just fine.

Jonathon.

laserlight

That should work since PHP strings have a zero-value.

It does seem a bit of an unnecessary hack to me though.

You could use the [man]ctype_alpha/man and [man]ctype_digit/man functions, especially since a non-numeric string could have non-alphabetic characters as well.

khaine

Or you could just use is_numeric().

Mark.

drawmack

if(eregi("[A-Z]",$Var) {//process character}
else {//process integer}

if(eregi("[0-9]",$Var) {//process integer}
else {//process character}

c'mon everyone how many other ways are there to do this?

coreyp_1

c'mon everyone how many other ways are there to do this?

You could check the ord() (ascii) value of the character, and if it is in the range of numbers, then it is a number, etc.

You could also populate an array with the numeric characters, and use the in_array() function.

No need to write the code, though. is_numeric() works fine (and was my first thought).

Although of all the solutions proposed, I like multiplying by 1 the best...

khaine

c'mon everyone how many other ways are there to do this?

Sounds like a challenge to me.. 😃

How about looping through the string character by character and comparing each one to an array of numerics and accepted delimiters. i.e. ',' and '.' to see if each on fits.

Mark.

laserlight

How about looping through the string character by character and comparing each one to an array of numerics and accepted delimiters. i.e. ',' and '.' to see if each on fits.

um, the string is of only 1 character.
ctype_digit() etc works this way, but is faster than if you do it with your own PHP code.
It should be faster than is_numeric() too, since the latter has to consider somewhat more complex rules.
That should be why regex is overkill too.
Of course for a single char speed actually doesnt make a difference, so...
lol

is_numeric() works fine

It works fine simply for differentiating between a single digit and a single non-digit.

It wont be so accurate if thenetbrainbox defined special characters as being non-letters.

khaine

er I was joking, The code I suggested would be a bit long winded to do what is already there. Lets just count it as a moment of madness.

The only down side to using any of the ctype functions is the version of php being used. 4.2.0 has them enabled by default earlier versions don't ( please correct me if Im wrong here ) so the ctype functions may not be available.

on a side note how about this for numeric checking not my code its from the user comments in the manual


$val = -123.45E293;
$match = '^-?\d+(?:\.\d+)?(?:[Ee]-?\d+)$';
if (preg_match('|' . $match . '|', $val)){
 echo $val . ' is a number!';
} else {
 echo $val . ' is not a number!';
}

or how about


<?
// there is a function called "is_numeric" in PHP, so i call this one
// "is_it_number"
// one probably does not have to initialize the variables like i do, but
// i'm used to PL/SQL requirements so ...
// this function will allow the tested string to include only
// digits and only one . (dot) or , (comma). neither of both
// can be a trailing character of the string.
// please note that we do not check here if the string is an empty string
//
function is_it_number($str_in) {
  $c1 = 0;
  $c2 = 0;
  for ($i = 0; $i < strlen($str_in); $i++)
  {
     if (preg_match("/[0-9]|[.,]/", substr($str_in,$i,1))) {
        ;;
     }
     else {
        $c1++;
     }
     if (preg_match("/[.,]/", substr($str_in,$i,1))) {
        $c2++;
     }
  }
     if ($c1 > 0 or $c2 > 1 or preg_match("/[.,]$|[ ]+/", $str_in)) {
        return (boolean) FALSE;
     }
     else {
        return (boolean) TRUE;
     }
}
?>

Again long winded ways to use is_numeric

Mark.

p.s. what a long and pointless post 🙂

Threehearts

Isn't there some way around to do this in a processor-friendly low cycle way?
shouldnt it be possible the have it right shift and discerning the nature by the number of times it needs to reach zero? something like that...

sorry if that sounded dumb but im not really into binaries... (as my awfully failed try to learn something about assembler a few years back is ample proof of)

jakob

drawmack

Well, since you're only checking one character you could to this

<?php
$int = ord($var);
if($int < 10) {//we've got a number here}
else {//we've got a character here}

laserlight

um, Threehearts, did you read the original question?

khaine is just hacking for fun, with no concern for efficiency.

The only down side to using any of the ctype functions is the version of php being used. 4.2.0 has them enabled by default earlier versions don't

That should be true, but if PHP has been compiled with them, they should be used if feasible.

EDIT:
drawmack, your code wont work, since ord() returns ASCII values.

khaine

I think thenetbrainbox was happy with the first answer given I just couldn't resist the

c'mon everyone how many other ways are there to do this?

from drawmack as for

<?php 
$int = ord($var); 
if($int < 10) {//we've got a number here} 
else {//we've got a character here}

It could work you would just have to use the ascii values for the numerics something like.

$int = ord($var); 
if( ($int < 58) && ($int > 47)) 
{
    //we've got a number here
} 
else 
{
    //we've got a character here
}

just one more daft way of doing it would be


$val="9";
switch($val)
{
    case 0  :
    case 1  :
    case 2  :
    case 3  :
    case 4  :
    case 5  :
    case 6  :
    case 7  :
    case 8  :
    case 9  : echo "This is a number";
                  break;
    default : echo "Not a Number";
                  break;
}

I agree that the ctype functions are perfectly feasible. The answers that should be taken seriously are

multiply by 1
ctype_alpha/ctype_digit combo
is_numeric

These are all good solutions as for writing a little function to do it, well why reinvent the wheel?

I shall now stop with the odd methods of doing things and go back to sleep.

Mark.

Threehearts

sure i read that.
but i stick to einstein when he said that solutions should "look good"...
grin
thats the fun of it, is it not?

jakob

drawmack

Originally posted by laserlight
drawmack, your code wont work, since ord() returns ASCII values.

my bad that would be between 48 and 57