PHP Do-While循环

Question

Below is my unfinished code. The last bit decided to throw a infinite loop. I am trying to create a random number script that will not repeat a number out of the 7 random picks. It seems once I added the || on the very last line the script starts to loop. Can anyone tell me what I'm doing wrong?

<?php 

$n1 = rand(1, 12);
$n2 = rand(13, 21);
$n3 = rand(15, 27);
$n4 = rand(20, 38); 
$n5 = rand(30, 46);
$n6 = rand(39, 49);
$bo = rand(1, 49);

// First number
echo $n1 . " ";

// Second number
do {
    echo $n2 . " ";
} while ($n1 == $n2);

// Third Number
do {
    echo $n3 . " ";
} while ($n3 == $n2 || $n1);

?>

Answer 1

$n1 is allways different from 0 then

do {
    echo $n3 . " ";
} while ($n3 == $n2 || $n1);  //<-- allways true

Answer 2

What @Majid said was correct. Check PHP's operator precedence .

The == operator precedes || operator for execution, so as long as $n1 is not false -y, the loop never exits.

Answer 3

Not sure what exactly you are trying to do, but your last do while loop is configured incorrectly. The below is more correct and wont give you an infinite loop.

do {
 $n3 = rand(15, 27);
 echo $n3 . " ";
} while (($n3 == $n2) || ($n3 == $n1));

Answer 4

There are a lot of issues here, but here's a start on the right path. Comments are inline.

<?php 

$n1 = rand(1, 12);
$n2 = rand(13, 21);

// First number
echo $n1 . " ";

// Second number
// no loop needed as your rand doesn't overlap your $n1
echo $n2 . " ";

// Third Number
do {
    $n3 = rand(15, 27); // this needs to be in your loop so when its the same it will generate a new number
} while ($n3 == $n2) // your || isn't needed as it can't over lap your $n2

echo $n3 . " ";

// Fourth Number
do {
    $n4 = rand(20, 38); // this needs to be in your loop so when its the same it will generate a new number
} while ($n4 == $n3)

echo $n4 . " ";

// ... repeat 

// Seventh Number
do {
    $bo = rand(1, 49); // this needs to be in your loop so when its the same it will generate a new number
} while ($bo == $n1 || $bo == $n2 || $bo == $n3 || $bo == $n4 || $bo == $n5 || $bo == $n6) // use your || to check against all of your variables

echo $bo;

?>

Answer 5

yes - Majid is right, this will most always be an infinite loop. What you might want is something similar to:

$previousNums = array();

for ($i = 0; $i < 7; $i++)
{
  $try = rand(0, 49);
  while (in_array( $try, $previousNums ) ) {
    // means we have already used this num, so try again
    $try = rand(0, 49);
  } 
  // append this num in the list of previousNums
  $previousNums[] = $try;

  echo ' num = ' . $try;
}

Answer 6

The priority of || is lower than == so actually it is more like this:

while(($n3 == $n2)||$n1))

and I think this is not you want so change it to

while(($n3 === $n2)||($n3 === $n1))

And please keep in mind to use === for comparing.

I hope it helps