php中var_dump()函数的详解说明_PHP教程

$a = "alsdflasdf;a";
$b = var_dump($a);
echo "
";
//var_dump($c);
$d=var_dump($c);
echo "
";
echo $a;
echo "
";
echo $b;
echo "
";
输出：
string(12) "alsdflasdf;a"
NULL
alsdflasdf;a

	$a = array (1, 2, array ("a", "b", "c"));
var_dump ($a);

/* 输出： array(3) { [0]=> int(1) [1]=> int(2) [2]=> array(3) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" } }

*/

$b = 3.1; $c = TRUE; var_dump($b,$c);

/* 输出： float(3.1) bool(true)

*/ ?>

set_time_limit(50); $a = array(1,2,3); $b = array('a'=>1, 'b'=>2, 'c'=>3); $c = array('a'=>array(1,2,3), 'b'=>array(4,5,6));

$time1 = microtime(true);

$times = 1000000; #10w

for($i=1; $i<=$times; $i++){ $A = var_export($a, true); }

$time2 = microtime(true);

for($i=1; $i<=$times; $i++){ $B = var_export($b, true); }

$time3 = microtime(true);

for($i=1; $i<=$times; $i++){ $C = var_export($c, true); }

$time4 = microtime(true);

for($i=1; $i<=$times; $i++){ $X = serialize($a); }

$time5 = microtime(true);

for($i=1; $i<=$times; $i++){ $Y = serialize($b); }

$time6 = microtime(true);

for($i=1; $i<=$times; $i++){ $Z = serialize($c); }

$time7 = microtime(true);

for($i=1; $i<=$times; $i++){ $O = unserialize($X); }

$time8 = microtime(true);

for($i=1; $i<=$times; $i++){ $P = unserialize($Y); }

$time9 = microtime(true);

for($i=1; $i<=$times; $i++){ $Q = unserialize($Z); } $time10 = microtime(true);

$var_export_time['a'] = $time2 - $time1; $var_export_time['b'] = $time3 - $time2; $var_export_time['c'] = $time4 - $time3;

$serialize_time['a'] = $time5 - $time4; $serialize_time['b'] = $time6 - $time5; $serialize_time['c'] = $time7 - $time6;

$unserialize_time['a'] = $time8 - $time7; $unserialize_time['b'] = $time9 - $time8; $unserialize_time['c'] = $time10 - $time9; print_r($var_export_time); print_r($serialize_time); print_r($unserialize_time); ?> output: Array( [a] => 3.3401498794556 [b] => 5.1394801139832 [c] => 8.8483898639679)Array( [a] => 1.6063709259033 [b] => 1.7033960819244 [c] => 3.4534389972687)Array( [a] => 1.6037359237671 [b] => 1.817803144455 [c] => 3.7992968559265)