What does the .= operator mean in PHP?

Question

I have a variable that is being defined as

$var .= \"value\";

How does the use of the dot equal function?

Answer 1

In very plain language, what happens is that whatever is stored in each variable is converted to a string and then each string is placed into a final variable that includes each value of each variable put together.

I use this to generate a random variable of alpha numeric and special characters. Example below:

function generateRandomString($length = 64) {
    $characters = '0123456789-!@#$%^*()?:abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = mb_strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

then to get the value of $randomString I assign a variable to the function like so

$key = generateRandomString();
echo $key;

What this does is pick a random character from any of the characters in the $characters variable. Then .= puts the result of each of these random "picks" together, in a new variable that has 64 random picks from the $characters string group called $randomString.