Php-mysql Course

To get a random number in PHP, you can use the mt_rand() function (there is also rand() function, but, according to PHP documentation, mt_rand() is faster).
- Example:
$nr = mt_rand();
echo $nr;

• To get a random number between a minimum and maximum number, use this syntax:   mt_rand($min, $max).
$nr = mt_rand(1000, 9999);
echo $nr;

Random numbers from array

If you have an array of numbers, and you want to get an random number from that array, you can use the array_rand() function. This function returns the key for a random entry.
- Example:
$nrs = array(123, 567, 4556, 34245, 78);
$rk = array_rand($nrs);
$nr = $nrs[$rk];
echo $nr;       // 4556

• If you want to pick more than one random key from array, add a seccond argument that specifies the number of keys (less than the number of elements of that array). In this case, array_rand($array, $nrk) will return an array with $nrs number of random keys from $array.
$nrs = array(123, 567, 4556, 34425, 78, 789);
$rks = array_rand($nrs, 2);     // contains 2 random keys (2, 5)

echo $nrs[$rks[0]];      // 4556
echo $nrs[$rks[1]];      // 789

Random number with distinct digits

If you want to get a random number between a minimum and maximum number, but with distinct digits, without repeated character in the random number, you can use the following function.
<?php
// returns a random number between $min and $max, with distinct digits
function getDistinctNr($min, $max) {
 // random number with distinct digits ( https://coursesweb.net )
  $nrstr = (string) mt_rand($min, $max);     // get random number, converted into string
  $n_nr = strlen($nrstr);           // number of characters
  $setnr = array();           // to store distinct digits that will form the returned number

  // traverse the characters of $nrstr to add in $setnr only its distinct digits
  // if number already in $setnr, traverse 0 to 9 to define another distinct number
  for($i=0; $i<$n_nr; $i++) {
    if(!in_array($nrstr[$i], $setnr)) $setnr[] = $nrstr[$i];
    else {
      for($i2=0; $i2<10; $i2++) {
        if(!in_array($i2, $setnr)) {
          $setnr[] = $i2;
          break;
        }
      }
    }
  }

  return implode('', $setnr);
}

// Test
$nr = getDistinctNr(1000, 9999);
echo $nr;
?>

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
What attribute makes an option from <select> selected?
checked="checked" selected="selected" disabled="disabled"
<select name="a_name">
 <option value="val1">Option 1</option>
 <option value="val2" selected="selected">Option 2</option>
</select>
What CSS value allows to create color gradients for background?
contain repeat-x linear-gradient
#id {
  background: linear-gradient(top left, #1f1, #fff, #11f);
}
What statement creates an array in JavaScript?
[] {} new Object()
var arr = [1, "CoursesWeb.net", "MarPlo.net"];
alert(arr[2]);
Indicate the PHP function used to redirect to other page.
function() header() switch()
header("Location: http://coursesweb.net/");
exit;
Random numbers in PHP

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