If-else¶

But instead of rendering nothing if there is no age, let’s print “Unknown”. We can do this by adding an optional else part to our if:

if (array_key_exists('age', $cutePet)) {
    echo $cutePet['age'];
} else {
    echo 'Unknown';
}

When we refresh, it works! You’ll use if statements all the time, both with and without the optional else part.

Combining If Conditions¶

Let’s complicate things again by removing the age of another pet. But this time, don’t remove the whole key, just set the age to an empty string.

{
    "name": "Chew Barka",
    "breed": "Bichon",
    "age": "",
    "weight": 8,
    "bio": "The park, The pool or the Playground - I love to go anywhere! I am really great at... SQUIRREL!",
    "image": "pet1.png"
}

When we refresh, we’re still free of errors. But the age for Chew Barka is missing. Since it’s blank, I would rather it say “Unknown”.

If we dump the $pets array and refresh, we can see that this makes sense:

<?php var_dump($cutePet);die; ?>
<?php foreach ($pets as $cutePet) { ?>
    ...
<?php } ?>

Chew Barka has an age key, so array_key_exists returns true, and the age - which is a blank string - is printed out. What we really want is for the code in the if statement to only run if the age key exists and isn’t blank.

Let’s do this first by adding a new if statement inside our existing one. We’ll check the age and only print it if it’s not empty:

if (array_key_exists('age', $cutePet)) {
    if ($cutePet['age'] != '') {
        echo $cutePet['age'];
    }
} else {
    echo 'Unknown';
}

The != is what you use when you want to compare 2 values to see if they are not the same. If the age is not empty, then this expression returns true and the echo runs.

Make sure also to add an else statement so that “Unknown” is printed if the age is empty:

if (array_key_exists('age', $cutePet)) {
    if ($cutePet['age'] != '') {
        echo $cutePet['age'];
    } else {
        echo 'Unknown';
    }
} else {
    echo 'Unknown';
}

This is all getting a little messy, but let’s try it! When we refresh, 2 pets have ages, 2 say “Unknown”, and we have exactly zero warnings. Nice!

The mess is that we have a lot of code for such a small problem. We also have the word “Unknown” written in 2 places. Code duplication is always a bummer because when you need to change this word later, you may forget about the duplication and only change it in one spot. Code duplication creates bugs!

Let’s simplify. Really, we want to print the age if the age key exists and is not an empty string. We can just put both of these conditions in one if statement:

if (array_key_exists('age', $cutePet) && $cutePet['age'] != '') {
    echo $cutePet['age'];
} else {
    echo 'Unknown';
}

The secret is the double “and” sign, or ampersand if we are being formal. An if statement can have as many parts, or expressions in it as you want. This if statement has two expressions, the array_key_exists part and the part that checks to see if the age is empty. Each returns true or false on its own. By using && between each expression, it means that every part must be true in order for the if statement to run. In other words, this is perfect.

Refreshing this time shows that things work just like before. But now our code is shorter, easier to read, and has no pesky duplication.

If-else-if¶

By now, you probably know that as soon as we get things working, I’ll challenge us by adding something harder! Imagine that sometimes the dog owner knows the age of her dog, but purposefully wants to hide it. Let’s change the age of Spark Pug to “hidden”.

{
    "name": "Spark Pug",
    "breed": "Pug",
    "age": "hidden",
    "weight": 11,
    "bio": "You want to go to the dog park in style? Then I am your pug!",
    "image": "pet2.png"
}

When we see this, let’s print a friendly message to contact the owner for the age.

We already have all the tools to make this happen, using another nested if statement:

if (array_key_exists('age', $cutePet) && $pet['age'] != '') {
    if ($cutePet['age'] == 'hidden') {
        echo '(contact owner for age)';
    } else {
        echo $cutePet['age'];
    }
} else {
    echo 'Unknown';
}

It works perfectly!

But let’s see if we can flatten our code to use just one level of an if statement. There’s nothing wrong with nested if statements, but sometimes they’re harder to understand. We really have just 3 possible scenarios:

1. The age key does not exist or is blank. We print “Unknown”.
2. The age key is equal to the string “hidden”. For this, print our nice message about contacting the owner.
3. And if those other conditions don’t apply, print the age!

When we had only one scenario, we just used an if. When we had two scenarios, we used an if-else. For 3 or more, we’ll go crazy with an if-elseif:

if (condition #1) {
    echo 'Unknown';
} elseif (condition #2) {
    echo 'Hi! Email the owner for the age details please!';
} else {
    echo $cutePet['age'];
}

This is really how it looks, except for the “condition #1” and “condition #2” parts where we’ll put real code that returns true or false. Like with the simple if, the else is optional, and you can actually have as many elseif parts as you want depending on how many different scenarios you have.

if (!array_key_exists('age', $cutePet) || $cutePet['age'] == '') {
    echo 'Unknown';
} elseif ('Condition #2') {

} else {

}

// sets the age key to an empty string
$cutePet['age'] = '';

if (!array_key_exists('age', $cutePet) || $cutePet['age'] == '') {
    echo 'Unknown';
} elseif ($cutePet['age'] == 'hidden')
    echo '(contact owner for age)';
} else {
    echo $cutePet['age'];
}

if (!array_key_exists('age', $cutePet) || $cutePet['age'] == '') {
    echo 'Unknown';
} elseif ($cutePet['age'] == 'hidden') {
    echo '(contact owner for age)';
} else {
    echo $cutePet['age'];
}