函数
PHP函数使用说明，应用举例，精简点评,希望对您学习php有所帮助。
1.print_r()
打印关于变量的易于理解的信息，若为数组，则显示数组的结构信息.
例如：
<br><?php <br/> $a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x', 'y', 'z'));<br> print_r ($a);<br>?><br> axgle点评:查看任何数组的结构信息，是程序调试的必备工具。对于任何返回结果是数组的“函数”，只要print_r一下，一切底细一目了然！
2.var_export()
输出或返回一个变量的字符串表示
此函数返回关于传递给该函数的变量的结构信息，它和print_r() 类似，不同的是其返回的表示是合法的 PHP 代码。
您可以通过将函数的第二个参数设置为 TRUE，从而返回变量的表示。
例如:
<br><?php <br/>$a = array (1, 2, array ("a", "b", "c"));<br>var_export ($a);<br><br>echo "<hr>";<br><br>$v = var_export($a, TRUE);<br>echo $v;<br><br>?><br>
axgle点评:上面例子中，$v = var_export($a, TRUE)返回的是php代码噢~~那么您就可以把它保存为php文件。
保存为php文件做什么？呵呵，这可以用作“缓存”，当需要的时候，可以直接include它。
3.file()
file() 将文件作为一个数组返回。数组中的每个元素都是文件中相应的一行，包括换行符在内。如果失败 file() 返回 FALSE。
<br><?php <br/>// 将一个文件读入数组。<br>$lines = file('test.txt');<br><br>//查看这个数组的结构<br>print_r($lines); <br><br>?> <br>
axgle点评:file()函数是我接触php的初期让我非常惊讶的的一个函数。相比以前我在c语言和vb里对
文件读写的无比麻烦的经历，使得当时的我感觉再也没有比file()函数更方便的文件读写方式了。
4.phpinfo()
打印与php有关的信息，例如PHP版本，功能支持，全局变量等.
例如:
phpinfo();
?>
axgle点评:简单的一个函数，让你时刻了解php的飞速发展---若您密切关注php的发展的话~~~~
5.file_get_contents() (注:PHP 4 >= 4.3.0, PHP 5)
将整个文件读入一个字符串.file_get_contents() 函数是用来将文件的内容读入到一个字符串中的首选方法。如果操作系统支持还会使用内存映射技术来增强性能。
例如:
$data = file_get_contents('test.txt');
echo $data;
?>
6. file_put_contents (注:PHP 5)
将一个字符串直接写入文件.
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