PHP校验表单，检测字段是否为空，当表单中有未填写的字段，则会显示错误信息。
<html>
<body>
<form METHOD="POST" ACTION="ErrorCheck.PHP">
<h1>Contact Information</h1>
<label>Nickname:</label>
<input TYPE="TEXT" NAME="nickname">
<label>Title:</label>
<input TYPE="TEXT" NAME="title">
<br />
<input TYPE="SUBMIT" VALUE="Submit">
<br />
<input TYPE="RESET" VALUE="Clear the Form">
</form>
</body>
</html>
/**
* PHP校验表单，检测字段是否为空
*
* @param
* @arrange 512-笔记网： jb51.cc
**/
<html>
<body>
<?PHP
$errorcount=0;
if (!trim($_POST['nickname'])) {
echo "<br /><b>Nickname</b> is required.";
$errorcount++;
}
if (!trim($_POST['title'])) {
echo "<br /><b>Title</b> is required.";
$errorcount++;
}
if ($errors > 0)
echo "<br /><br />Please use your browser's back button " .
"to return to the form,and correct error(s)";
?>
</body>
</html>
/*** 来自编程之家 jb51.cc（jb51.cc） ***/
/**
* PHP校验表单，检测字段是否为空
*
* @param
* @arrange 512-笔记网： jb51.cc
**/
” ” (ASCII 32 (0×20)),an ordinary space.
“\t” (ASCII 9 (0×09)),a tab.
“\n” (ASCII 10 (0x0A)),a new line (line Feed).
“\r” (ASCII 13 (0x0D)),a carriage return.
“\0″ (ASCII 0 (0×00)),the NUL-byte.
“\x0B” (ASCII 11 (0x0B)),a vertical tab.
/*** 来自编程之家 jb51.cc（jb51.cc） ***/