Write a program in PHP to demonstrate the use of switch state and also show its output.

Sure, here is a simple PHP program that demonstrates the use of a switch statement:

<?php
$day = "Monday";

switch ($day) {
    case "Monday":
        echo "Today is Monday.";
        break;
    case "Tuesday":
        echo "Today is Tuesday.";
        break;
    case "Wednesday":
        echo "Today is Wednesday.";
        break;
    case "Thursday":
        echo "Today is Thursday.";
        break;
    case "Friday":
        echo "Today is Friday.";
        break;
    case "Saturday":
        echo "Today is Saturday.";
        break;
    case "Sunday":
        echo "Today is Sunday.";
        break;
    default:
        echo "Invalid day.";
}
?>

In this program, we have a variable $day that holds the value "Monday". The switch statement checks the value of $day. If the value matches one of the cases, it executes the code for that case. If it doesn't match any case, it executes the default case.

The break keyword is used to prevent the code from running into the next case automatically.

The output of this program will be:

Today is Monday.