Turning a nested PHP if statement into a single if statement - php

Question

I am trying to figure out how to turn this nested if statement into a single if statement and having trouble getting it to run.
This is the original nested if statement:
if (isset($_REQUEST['gender']))
{
$gender = $_REQUEST['gender'];
if ($gender == 'M')
{
echo '<p><b>Good day, Sir!</b></p>';
}
elseif ($gender == 'F')
{
echo '<p><b>Good day, Madam!</b></p>';
}
else
{ // Unacceptable value.
$gender = NULL;
echo '<p class="error">Gender should be either "M" or "F"!</p>';
}
}
else
{ // $_REQUEST['gender'] is not set.
$gender = NULL;
echo '<p class="error">You forgot to select your gender!</p>';
}
This is my attempt:
if (isset($_REQUEST['gender']) && $gender == 'M')
{
$gender = $_REQUEST['gender'];
echo '<p><b>Good day, Sir!</b></p>';
}
elseif (isset($_REQUEST['gender']) && $gender == 'F')
{
$gender = $_REQUEST['gender'];
echo '<p><b>Good day, Madam!</b></p>';
}
elseif (isset($_REQUEST['gender']) && $gender != 'M' || (isset($_REQUEST['gender']) && $gender != 'F')
{ // Unacceptable value.
$gender = $_REQUEST['gender'];
$gender = NULL;
echo '<p class="error">Gender should be either "M" or "F"!</p>';
}
else
{ // $_REQUEST['gender'] is not set.
$gender = NULL;
echo '<p class="error">You forgot to select your gender!</p>';
}
I am not sure if it's because the $gender = $_REQUEST['gender']; is not executing, but any help would be appreciated.

Answer 1

You're checking variable $gender before you assign value to it. Following will help,
$gender = isset($_REQUEST['gender']) ? $_REQUEST['gender'] : "";
if ($gender == 'M')
{
echo '<p><b>Good day, Sir!</b></p>';
}
else if($gender == 'F')
{
echo '<p><b>Good day, Madam!</b></p>';
}
else if (!empty($gender) && ($gender != 'M' || $gender != 'F'))
{ // Unacceptable value.
echo '<p class="error">Gender should be either "M" or "F"!</p>';
}
else
{
echo '<p class="error">You forgot to select your gender!</p>';
}

Answer 2

A switch statement might be cleaner here.
switch ($_REQUEST['gender']) {
case null:
echo '<p class="error">You forgot to select your gender!</p>';
break;
case 'M':
echo '<p><b>Good day, Sir!</b></p>';
break;
case 'F':
echo '<p><b>Good day, Madam!</b></p>';
break;
default:
echo '<p class="error">Gender should be either "M" or "F"!</p>';
}

Answer 3

Here's the untested way I'd do this. I'd also do client side(javascript) checks first. I'm also presuming your gender field is text if is select you could take out the strtolower and trim.
<?php
if (empty($_REQUEST['gender']) || (strtolower(trim($_REQUEST['gender'])) != 'm' && strtolower(trim($_REQUEST['gender'])) != 'f')) {
//this should probably be checked client side for better usability, but better to check server side that we trust the data
echo '<p class="error">Please enter a valid Gender</p>';
} else {
$gender = strtolower(trim($_REQUEST['gender']));
echo '<p><b>Good day, ';
if ($gender == 'm') {
echo 'Sir!</b></p>';
} else {
echo 'Madam!</b></p>';
}
}