我正在使用相同的变量检查这4个字符串的执行时间差异：
$name= "rahul";
echo "My name is $name"
echo "My name is ".$name;
echo "My name is {$name}";
echo "My name is '{$name}'";
但每次我尝试过它我只得到3或4个随机答案，即。 0 OR 0.00099992752075195 OR 0.0010001659393311
我的代码是：
<?php
function microtime_float()
{
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
$name = 'rahul' ;
$time_start = microtime_float();
echo "My name is $name"; // First style
$time_end = microtime_float();
$time = $time_end - $time_start;
echo " // $time seconds\n ";
$time_start2 = microtime_float();
echo "My name is ".$name; // Second style
$time_end2 = microtime_float();
$time2 = $time_end2 - $time_start2;
echo " // $time2 seconds\n ";
$time_start3 = microtime_float();
echo "My name is {$name}"; // Third style
$time_end3 = microtime_float();
$time3 = $time_end3 - $time_start3;
echo " // $time3 seconds\n";
$time_start4 = microtime_float();
echo "My name is '{$name}'"; // Fourth style
$time_end4 = microtime_float();
$time4 = $time_end4 - $time_start4;
echo " // $time4 seconds\n";
?>
我是通过cmd计算的，我的输出是：
C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0.00099992752075195 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is rahul // 0.0010001659393311 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0.00099992752075195 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0.00099992752075195 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0.00099992752075195 seconds My name is rahul // 0 seconds My name is rahul // 0 seconds My name is 'rahul' // 0.0010001659393311 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.0010001659393311 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0.00099992752075195 seconds My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0.0010001659393311 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0 seconds My name is rahul // 0.0010001659393311 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is rahul // 0 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>php q.php My name is rahul // 0 seconds My name is rahul // 0.00099992752075195 seconds My name is rahul // 0.00099992752075195 seconds My name is 'rahul' // 0 seconds C:\wamp\www\my_jquery>
为什么我会一次又一次地使用不同的声明获得相同的输出。
答案 0 :(得分：2)
差异很小。尝试重复每个动作至少10000次，然后你应该看到任何可比的结果。你不需要使用echo，分配给另一个var将会起作用。
为什么你的结果如此随机？由于结果时间非常短，因此任何其他服务器进程都可能会影响您的结果。试试这个版本：
<?php
function microtime_float()
{
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
$times = 10000;
$name = 'rahul' ;
$time_start = microtime_float();
// Make loop
for($i = 0; $i < $times; $i++) {
$testvar = "My name is $name"; // First style
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo " // $time seconds\n ";
//and same for other styles
?>
此外，许多其他开发人员证明最佳解决方案是使用
echo 'My name is ' . $name;
答案 1 :(得分：2)
这些语句执行时间不到1毫秒。由于精度为1毫秒，因此无法获得有意义的结果。
如果要对此进行基准测试，则必须迭代很多次，例如10000次。
此外，您的基准测试不允许您测量字符串表示之间的差异，因为字符串通过echo的输出比表达式的评估花费更多的时间。
答案 2 :(得分：0)
脚本的执行时间实际上可以忽略不计。为了获得清晰的结果，您应该使用带有100.000次迭代的循环语句，例如每个语句。