php M or F (male or female)

I know there are more elegant ways to set up an html form to take the input of male or female; however, I am learning, and I was just wondering if this is also possible:

//Incorpor开发者_开发技巧ate two checks
 if (empty($_POST['sex'])==FALSE && sanityCheck($_POST['sex'], 'string', 1)==TRUE)
      {
      // if the checks are ok for  sex we assign sex  to a variable
      $sex = $_POST['sex'];
       }
      else
      {
      // if all is not well we echo an error message
      echo 'Please enter a valid Gender';
      // and exit the script
      exit();
      }

If so, how would I check this with regex? Whether the user typed M or F.

I am thinking:

function checksex($sexcheck)
{
//Some regex here to check the sex?
  return preg_match('               ', $sexcheck);
}

And then call checksex as a third check added to the if conditional, like this:

if (empty($_POST['sex'])==FALSE && sanityCheck($_POST['sex'], 'string', 1) != FALSE && checksex($_POST['sex'], 1) ==TRUE)
{
...
}

To check if the user typed M or F, all you would need to do is a string comparison. No need for regex

if ( isset($_POST['sex']) ){
    $sex = $_POST['sex'];
    if ( $sex == 'M' ){
        echo 'Male';
    }else if ( $sex == 'F' ){
        echo 'Female';
    }else{
        echo 'Please enter a valid Gender';
    }
}else{
    echo 'Please enter a valid Gender';
}

However, rather than having the user type out M or F, why not use a select box or Radio Buttons ?

A select box may look something like this

<select name='sex'>
    <option selected="yes" value="NA">Not Saying</option>
    <option value="F">Female</option>
    <option value="M">Male</option>
 </select>

Or radio buttons:

<input type="radio" name="sex" value="M" /> Male <br />
<input type="radio" name="sex" value="F" /> Female

You would of course still have to check that $_POST['sex'] is still M or F, and handle the case where it isn't either of them, as the user may decide to post an invalid value.

Try this "(M|F){1}" without the quotes

How about

// check if the sex variable is 'f' or 'm'
        $sex = ($_POST['sex'] == 'f' || $_POST['sex'] == 'm') ? $_POST['sex'] : false;
// thanks to peter
    // if $sex is false then echo..
        if (!$sex)
            echo ('Please enter a valid Gender');

Explaination

its a conditional operator called Ternary Operator. Its like

(if clause) ? (then) : (else);

Or

(expr 1) ? (expr 2) : (expr 3);

expr 2 is evaluated if expr 1 is true expr 3 is evaluated if expr 1 is false

Ref : http://php.net/manual/en/language.operators.comparison.php

$s = $_POST['sex'];

if(isset($s) && $s == 'M') {
    $sex = "Male";
} elseif(isset($s) && $s == 'F') {
    $sex = "Female";
} else {
    $sex = "Please enter a valid gender";
}