The do-while loops are very similar to while loops, do-while loops checked the expression at the end of iteration.
do
{
 //execute the statement; 
}
while(expression)
$i = 1;
do {
    echo $i++;
} while ($i < 5);
//output: 1234
The first iteration of a do-while loop is guaranteed to run because condition is checked at last
$i = 1;
do {
    echo $i;
} while ($i > 1);
//output: 1