Die() and Exit()

In a recent interview, an experienced php developer was asked the difference between die() and exit(). The gentleman was shocked but he did manage to give a convincing answer. There are plenty of articles on the Internet on this topic which says they are both the same and there are many others who argue for and against the notion that both die() and exit() are not the same.So, let us discuss and try to reach a conclusion on what exactly is the difference between die() and exit() in php.

According to the php manual from php.net, both die() and exit() are language constructs. The manual also goes on to say that die() is an alias of exit() and vice-versa. Honestly, there are not many differences between these two language constructs except for the the fact that die starts with a ‘d’ and exit starts with an ‘e’. To prove this let us play with a few examples.

for($i = 0; $i < 10; $i++)
{
    if ($i == 2)
    {
        exit("\n Using exit(), We are done");
    }
}

Now let us look at the same example using die();

for($i = 0; $i < 10; $i++)
{
    if ($i == 2)
    {
        die("\n Using die(), We are done");
    }
}

The output for each of these will be: “Using exit(), We are done Using die(), We are done” respectively. Now let us try each of these to output a number.

for($i = 0; $i < 10; $i++)
{
    if ($i == 2)
    {
        exit(-1);
    }
}

Looking at the output for the same example using die();

for($i = 0; $i < 10; $i++)
{
    if ($i == 2)
    {
        die(-1);
    }
}

These examples were edited using a textpad editor. The output for both the above cases were “Tool completed with exit code -1”.

So, the honest answer to the question “What is difference between die() and exit() in php” IS – There is not a single visible difference between these two functions. They both are the same, one is the alias of the other. If at all any one of you can find a real visible difference then I would appreciate if you could post it in the comments section of this blog.

Till next time, Happy PHP programming!