我已经查看了关于 ob_start() ob_end_clean() ob_end_flush() 的 php 手册。我已经看到了关于该主题的不同示例,无论如何我修改了该示例,但此时我很困惑。这是脚本。
ob_start();
echo "Hello x, ";
ob_start();
echo "Hello y, ";
ob_start();
echo "Hello z, ";
ob_start();
echo "Hello World";
$ob_2 = ob_get_contents();
ob_end_clean();
echo "Galaxy";
$ob_1 = ob_get_contents();
ob_end_clean();
echo " this is OB_1 : ".$ob_1;
echo "<br> and this is OB_2 : ".$ob_2;
该脚本的输出是:
你好 x,你好 y,这是 OB_1:你好 z,Galaxy
这是 OB_2:你好世界
--------------------------------------------------------
为什么输出不是这样的?
这是 OB_1:你好 x,你好 y,你好 z,Galaxy
这是 OB_2:你好世界
我错过了什么?
我将注释您的代码以解释发生了什么。所有输出缓冲区都初始化为空,这是标准的:
ob_start(); // open output buffer 1
echo "Hello x, "; // echo appended to output buffer 1
ob_start(); // open output buffer 2
echo "Hello y, "; // echo appended output buffer 2
ob_start(); // open output buffer 3
echo "Hello z, "; // echo appended to output buffer 3
ob_start(); // open output buffer 4
echo "Hello World"; // echo appended output buffer 4
$ob_2 = ob_get_contents(); // get contents of output buffer 4
ob_end_clean(); // close and throw away contents of output buffer 4
echo "Galaxy"; // echo appended to output buffer 3
$ob_1 = ob_get_contents(); // get contents of output buffer 3
ob_end_clean(); // close and throw away contents of output buffer 3
// at this point, $ob_2 = "Hello World" and $ob_1 = "Hello z, Galaxy"
// output buffer 1 = "Hello x," and output buffer 2 = "Hello y,"
echo " this is OB_1 : ".$ob_1; // echo appended to output buffer 2
// output buffer 2 now looks like "Hello y, this is OB_1 : Hello z, Galaxy"
echo "<br> and this is OB_2 : ".$ob_2; // echo appended to output buffer 2
// output buffer 2 now looks like:
// "Hello y, this is OB_1 : Hello z, Galaxy<br> and this is OB_2 : Hello World"
// output buffer 2 implicitly flushed by end of script
// output from buffer 2 captured by (appended to) output buffer 1
// output buffer 1 now looks like:
// "Hello x, Hello y, this is OB_1 : Hello z, Galaxy<br> and this is OB_2 : Hello World"
// output buffer 1 implicitly closed by end of script. This is when your output
// actually gets printed for this particular script.
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