Linux, Apache, MySQL, PHP

foreach($test_array as $x)
{
    echo $x."<br>";
     if($x==0 && is_numeric($x))

String conversion to numbers
When a string is evaluated in a numeric context, the resulting value and type are determined as follows. 

If the string does not contain any of the characters '.', 'e', or 'E' and the numeric value fits into integer type limits (as defined by PHP_INT_MAX), the string will be evaluated as an integer . In all other cases it will be evaluated as a float . 

The value is given by the initial portion of the string . If the string starts with valid numeric data, this will be the value used. Otherwise, the value will be 0 (zero). Valid numeric data is an optional sign, followed by one or more digits (optionally containing a decimal point), followed by an optional exponent. The exponent is an 'e' or 'E' followed by one or more digits. 

For more information on this conversion, see the Unix manual page for strtod(3).

Return Value
On success, the function returns the converted floating point number as a double value.
If no valid conversion could be performed, a zero value (0.0) is returned.
If the correct value is out of the range of representable values, a positive or negative HUGE_VAL is returned, and the global variable errno is set to ERANGE.
If the correct value would cause underflow, zero is returned and errno is set to ERANGE.

If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically. These rules also apply to the switch statement. The type conversion does not take place when the comparison is === or !== as this involves comparing the type as well as the value.

<?php
var_dump(0 == "a"); // 0 == 0 -> true
var_dump("1" == "01"); // 1 == 1 -> true
var_dump("10" == "1e1"); // 10 == 10 -> true
var_dump(100 == "1e2"); // 100 == 100 -> true

switch ("a") {
case 0:
    echo "0";
    break;
case "a": // never reached because "a" is already matched with 0
    echo "a";
    break;
}
?> 

xx77abs wrote:

Can anyone explain to me

<?php<br />
<br />
$typecastme = array(<br />
  'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'<br />
);<br />
<br />
echo '<pre>';<br />
foreach ($typecastme as $int => $str) {<br />
  echo 'if('.$str.'=='.$int.') is: '.($str==$int?'TRUE':'FALSE')."\n";<br />
  echo ''.$str.' as boolean is: '.((bool)$str?'TRUE':'FALSE')."\n";<br />
  echo ''.$str.' as integer is: '.(integer)$str."\n";<br />
  echo 'var_dump('.$str.'=='.$int.') is: ';<br />
  var_dump($str==$int);<br />
  echo 'var_dump((int)'.$str.'==0) is: ';<br />
  var_dump((int)$str==0);<br />
  echo "\n";<br />
}<br />
echo '</pre>';

pc.bharti wrote:

I am new to Linux. CAn anyone tell me which is the best and fastest way to get acquaint with it??