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Thread: ctype and int

  1. #1
    Senior Coder doubledee's Avatar
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    ctype and int

    Why does this code fail and take the ELSE branch...

    PHP Code:
        if (isset($_GET['comment']) && $_GET['comment']){
            
    // CommentID Found in URL.
            // Cast to Integer.
            
    $commentID = (int)$_GET['comment'];


            
    // Check CommentID Format.
            
    if ((ctype_digit($commentID)) && ($commentID 0)){
                
    // Valid CommentID
                // Continue processing...

            
    }else{
                
    // Invalid CommentID 

    Is it because an Integer can be negative and thus have a minus sign in it?

    Sincerely,


    Debbie

  • #2
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    From php.net:



    Your integer WILL return false. If you look at the manual for the function it shows the parameter as a string:



    You are casting it to an integer and then passing it in as a parameter.

    Instead, use the is_numeric() function as it will take strings and integers and return true if either are numerical.
    I can't really think of anything to write here now...

  • #3
    Senior Coder doubledee's Avatar
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    Quote Originally Posted by tangoforce View Post
    From php.net:



    Your integer WILL return false. If you look at the manual for the function it shows the parameter as a string:



    You are casting it to an integer and then passing it in as a parameter.

    Instead, use the is_numeric() function as it will take strings and integers and return true if either are numerical.
    So even a positive Integer fails.

    Interesting.

    Guess I have been technically using this the wrong way, but since I use it with URL validation, I get by.


    I don't like isnumeric() because I only want to check for positive whole numbers (i.e. "natural" numbers).

    Sincerely,


    Debbie

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    Quote Originally Posted by doubledee View Post
    So even a positive Integer fails.

    Interesting.
    It doesn't fail, the function deliberately returns a false result because it only accepts a string. If it is not a string, it will return false. You could think of it like this:

    PHP Code:
    function ctype_digit($Var)
       {
       if (
    is_string($Var))
          {
          return (
    is_numeric($Var))? truefalse;
          }
       else
          {
          return 
    false
          
    }
       } 

    Quote Originally Posted by doubledee View Post
    Guess I have been technically using this the wrong way, but since I use it with URL validation, I get by.
    Thats the point, anything passed via the url / GET array IS a string. If you remove your line of code that casts it to an integer you should be ok

    Quote Originally Posted by doubledee View Post
    I don't like isnumeric() because I only want to check for positive whole numbers (i.e. "natural" numbers).
    So include a second clause in your if test (as your original code shows): ($Var > 0) - job done!
    I can't really think of anything to write here now...

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    Senior Coder doubledee's Avatar
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    Quote Originally Posted by tangoforce View Post
    It doesn't fail, the function deliberately returns a false result because it only accepts a string. If it is not a string, it will return false. You could think of it like this:

    PHP Code:
    function ctype_digit($Var)
       {
       if (
    is_string($Var))
          {
          return (
    is_numeric($Var))? truefalse;
          }
       else
          {
          return 
    false
          
    }
       } 
    That is a good way to think about things.


    Quote Originally Posted by tangoforce View Post
    Thats the point, anything passed via the url / GET array IS a string. If you remove your line of code that casts it to an integer you should be ok
    Yeah, I saw that.


    Quote Originally Posted by tangoforce View Post
    So include a second clause in your if test (as your original code shows): ($Var > 0) - job done!

    So, for what I am trying to do, which is better...

    Option #1:
    PHP Code:
        if (isset($_GET['page']) && $_GET['page']){
            
    // Page in URL.
            
    $currPage $_GET['page'];

            
    // Check Page-Format.
            
    if ((ctype_digit($currPage)) && ($currPage 0)){
                
    // Valid Page.

            
    }else{
                
    // Invalid Page.

            
    }
        } 

    Option #2:
    PHP Code:
        if (isset($_GET['page']) && $_GET['page']){
            
    // Page in URL.
            
    $currPage $_GET['page'];

            
    // Check Page-Format.
            
    if ((isnumeric($currPage)) && ($currPage 0)){
                
    // Valid Page.

            
    }else{
                
    // Invalid Page.

            
    }
        } 
    Sincerely,


    Debbie

  • #6
    Senior Coder Dormilich's Avatar
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    Quote Originally Posted by doubledee View Post
    I don't like isnumeric() because I only want to check for positive whole numbers (i.e. "natural" numbers).
    PHP Code:
    filter_input(INPUT_GET"comment"FILTER_VALIDATE_INT, ["options" => ["min_range" => 1]]); 
    The computer is always right. The computer is always right. The computer is always right. Take it from someone who has programmed for over ten years: not once has the computational mechanism of the machine malfunctioned.
    André Behrens, NY Times Software Developer

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    Take off (int) and it wont turn it into an integer then, it will be a string, then you can do that.


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