regular expression problem.

[redarrow]

advance thank you.

 

how the hell it letting the @ in, when only a-z 0-9 are allowed only.

 

madness

 

<?php

$message="my name is @ redarrow";

$err="Sorry you have not filled in the form correctly!";

if(!preg_match("/[a-z0-9]/i",$message)){

    echo $err;
   
}elseif(empty($message)){

echo $err;

}else{

echo $message;
}

?>

[AmandaF]

It's only matching one character.  /[a-z0-9]/i means "match anything that contains a letter or number".  What you want is /^[a-z0-9]*$/i or /^[a-z0-9]+$/i which will match either zero or more (if you use the *) or one or more (with the +) letters and numbers in between the beginning (^) and end ($) of the string (so nothing but letters and numbers will be accepted).

[Axeia]

What she said, and I wanted to add:

 

There is a regular expressions subforum (in this one even). Might yield better results there in the future.

[nrg_alpha]

It's only matching one character.  /[a-z0-9]/i means "match anything that contains a letter or number".  What you want is /^[a-z0-9]*$/i or /^[a-z0-9]+$/i which will match either zero or more (if you use the *) or one or more (with the +) letters and numbers in between the beginning (^) and end ($) of the string (so nothing but letters and numbers will be accepted).

 

There is a missing element to the character list however.. Since the goal is the check a message, you need to allow spaces (otherwiseallyourmessagewordswillneedtobebunchedtogether). So, assuming there is no punctuation (which in itself is weird), and the message can contain zero or more characters (which I assume is also the case if there is a empty($message) check), simply add the space to the zero or more character list:

 

/^[ a-z0-9]*$/i

 

If we want to include various whitespace characters, we can use \s instead of a literal space.

 

But all in all, I question the entire message system and the pattern that implies, simply for the sake that messages in real life contain more than [ a-z0-9]. As mentioned previously, this means no punctuation (so kiss periods, question marks, commas and the like goodbye).

[ghostdog74]

advance thank you.

 

how the hell it letting the @ in, when only a-z 0-9 are allowed only.

 

madness

 

<?php

$message="my name is @ redarrow";

$err="Sorry you have not filled in the form correctly!";

if(!preg_match("/[a-z0-9]/i",$message)){

    echo $err;
   
}elseif(empty($message)){

echo $err;

}else{

echo $message;
}

?>

 

$message="my name is @ redarrow";
if ( ctype_alnum ($message) ){
print "$message is alphanumeric\n";
}else{
print "'$message' is not alphanumeric\n";
}

[nrg_alpha]

$message="my name is @ redarrow";
if ( ctype_alnum ($message) ){
print "$message is alphanumeric\n";
}else{
print "'$message' is not alphanumeric\n";
}

 

ctype_alnum doesn't evaluate to true when there are spaces involved, so this would mean messages cannot have spaces.

[ghostdog74]

 

ctype_alnum doesn't evaluate to true when there are spaces involved, so this would mean messages cannot have spaces.

i only looked at his first post. if its not what he wants, then so be it.

[nrg_alpha]

Yeah, I know he mentions only a-z0-9, and if that's the case, then for sure, ctype_alnum would be the preferred method. I just found it strange that for a message, only those characters are permissible.

[Maq]

Yeah, I know he mentions only a-z0-9, and if that's the case, then for sure, ctype_alnum would be the preferred method. I just found it strange that for a message, only those characters are permissible.

 

Same here.  If you use ctype_alnum, it would be more difficult to modify than using a regex from the start.  But, yes, in this case ctype_alnum, would be ideal.