PHP判断字符串是纯英文、纯汉字或汉英混合

if(preg_match("/^[a-z]*$/i",   "fdsFDfd")) 

{ 

 echo   "全字母 

 "; 

 } 

比如：
var str = "php编程";
if (/^[u4e00-u9fa5]+$/.test(str)) {
alert("该字符串全部是中文");
}
else{
alert("该字符串不全部是中文");
} php中，是用x表示十六进制数据的。于是，变换成如下的代码：
$str = "php编程";
if (preg_match("/^[x4e00-x9fa5]+$/",$str)) {
print("该字符串全部是中文");
} else {
print("该字符串不全部是中文");
}

/^[a-z0-9_u4e00-u9fa5]+[^_]$/g utf-8下

preg_match("/^[a-z0-9_x80-xff]+[^_]$/g",$a);gbk下:

preg_match("/^[a-z0-9_".chr(0xa1)."-".chr(0xff)."]+[^_]$/",$a)

<?php
/**
 * PHP判断字符串纯汉字 OR 纯英文 OR 汉英混合
 * 琼台博客
 */
echo '<meta charset="utf-8" />';
function utf8_str($str){
    $mb = mb_strlen($str,'utf-8');
    $st = strlen($str);
    if($st==$mb)
        return '纯英文';
    if($st%$mb==0 && $st%3==0)
        return '纯汉字';
    return '汉英混合';
}
 
$str = '琼台博客';
echo '字符串：<span style="color:red">'.$str.'</span>，是<span style="color:red">'.utf8_str($str).'</span>';
?>

function gbk_str($str){
    $mb = mb_strlen($str,'gbk');
    $st = strlen($str);
    if($st==$mb)
        return '纯英文';
    if($st%$mb==0 && $st%2==0)
        return '纯汉字';
    return '汉英混合';
}

$username=$_REQUEST['username'];
if(!preg_match("/^[a-z0-9xa1-xff]{3,10}$/",$username))
 {
  echo"34r345";
  exit;
 }

<?php

header('Content-type: text/html; charset=utf-8');

$str = "dasdadsfsadASDSADS";

if (preg_match('/^[a-zA-Z]+$/',$str))
{
 echo $str."是字母";
}
else
{
 echo $str."不是字母";
}

?>

if(preg_match("/^d*$/",   "4312"))
{
echo   "全数字
";
}

if(preg_match("/^[a-z]*$/i",   "fdsFDfd"))
{
echo   "全字母
";
}

if(preg_match("/^[a-zd]*$/i",   "fd4fd34"))
{
echo   "有数字有字母
";
}

“” (an empty string)

0 (0 as an integer)

0.0 (0 as a float)

“0″ (0 as a string)

NULL

FALSE

array() (an empty array)

var $var; (a variable declared, but without a value in a class)

<?php
$a;
$b = false;
$c = '';
$d = 0;
$e = null;
$f = array();

?>

empty()

首先是empty的var_dump输出：

:
<?php
var_dump(empty($a));
var_dump(empty($b));
var_dump(empty($c));
var_dump(empty($d));
var_dump(empty($e));
var_dump(empty($f));
?>

程序输出为：
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)

从代码中可以看出，只要数据类型是否为空或假，empty()就输出true。
isset()

再看看isset的输出:
var_dump(isset($a));
var_dump(isset($b));
var_dump(isset($c));
var_dump(isset($d));
var_dump(isset($e));
var_dump(isset($f));

// 输出
bool(false)
bool(true)
bool(true)
bool(true)
bool(false)
bool(true)

可以看出isset()只能用来判断是否为NULL和未定义。
is_null()

最后是is_null的输出:
var_dump(is_null($a));
var_dump(is_null($b));
var_dump(is_null($c));
var_dump(is_null($d));
var_dump(is_null($e));
var_dump(is_null($f));

// 输出
bool(true)
bool(false)
bool(false)
bool(false)
bool(true)
bool(false)

<?php

$a=100;

$b="";

$c=null;

//isset检查

echo "isset","$a=$a",isset($a)?"define":"undefine","rn";

echo "isset","$b=$b",isset($b)?"define":"undefine","rn";

echo "isset","$c=$c",isset($c)?"define":"undefine","rn";

unset($b);

echo "isset","$b",isset($b)?"define":"undefine","rn";

$b=0;

echo "rnrn";

//empty检查

echo "empty","$a=$a",!empty($a)?"no empty":"empty","rn";

echo "empty","$b=$b",!empty($b)?"no empty":"empty","rn";

echo "empty","$c=$c",!empty($c)?"no empty":"empty","rn";

unset($b);

echo "empty","$b",!empty($b)?"no empty":"empty","rn";

$b=0;

echo "rnrn";

//is_null检查

echo "is_null","$a=$a",!is_null($a)?"no null":"null","rn";

echo "is_null","$b=$b",!is_null($b)?"no null":"null","rn";

echo "is_null","$c=$c",!is_null($c)?"no null":"null","rn";

unset($b);

echo "is_null","$b",is_null($b)?"no null":"null","rn";

/**
 * 序列号生成器
 */
function snMaker($pre = '') {
 $date = date('Ymd');
 $rand = rand(1000000,9999999);
 $time = mb_substr(time(), 5, 5, 'utf-8');
 $serialNumber = $pre.$date.$time.$rand;
// echo strlen($serialNumber).'<br />';
 return $serialNumber;
}
echo snMaker();

/**
 * 将一个字符串的一部分替换成某一特定字符
 * @param str or int $str 需要处理的字符串
 * @param str or int $to 将替换成什么字符串
 * @param int $start 保留前几个字符
 * @param int $end 保留后几个字符
 */
function hideString($str = 'hello', $to = '*', $start = 1, $end = 0) {
 $lenth = strlen($str) - $start - $end;
 $lenth = ($lenth < 0) ? 0 : $lenth;
 $to = str_repeat($to, $lenth);
 $str = substr_replace($str, $to, $start, $lenth);
 return $str;
}

echo hideString();

<?php

 /* 配置 */
 $key_sum = 1500;    //CD-Key最大数量,防止重复值
 $key_total = 1000;    //最终需要的CD-Key数量
 $limiter = "-";    //CD-Key每组数字之间的连接符
 $save_file = "./cd_key.txt"; //保存CD-Key文件
 $num_file = "./number.txt"; //序列数字文件
 $file = file($num_file);  //打开序列数文件
 $start_num = 0;    //最小随机数
 $end_num = count($file);  //最大随机数

 /* 生成随机数字串 */
 $cdkey = array();
 for ($i=0; $i<$key_sum; $i++)
 {
     $key_str = $file[rand_num($start_num, $end_num)].$limiter.
                         $file[rand_num($start_num, $end_num)].$limiter.
                         $file[rand_num($start_num, $end_num)].$limiter.
                         $file[rand_num($start_num, $end_num)];
      $cdkey[] = str_replace("rn", "", $key_str);
 }

 /* 过滤重复串并且提取最终需要的CD-Key数量 */
 $cdkey = array_unique($cdkey);
 $key_result = array();
 for ($i=0; $i<$key_total; $i++)
 {
     $key_result[] = $cdkey[$i];
 }

 /* 把最终的CD-Key写入文件 */
 $fp = fopen($save_file, "w+") or die("Open $save_file failed");
 fwrite($fp, implode("rn", $key_result)) or die("Write $save_file failed");
 unset($cdkey);
 unset($$key_result);
 fclose($fp);

 echo "Create $key_total key succeed!";

 /* 随机函数 */
 function rand_num($start, $end)
 {
     return mt_rand($start, $end);
 }

?>

for($k=2;$k<5;$k++)
{
 if(!empty(${'pfile'.$k}))
 { echo ${'pfile'.$k};}//那么相当于输出的是$pfile2,$pfile3.......}
}

<?php
$str = "Hello world. It's a beautiful day.";
print_r (explode(" ",$str));
?>

输出：

Array
(
[0] => Hello
[1] => world.
[2] => It's
[3] => a
[4] => beautiful
[5] => day.
)

/**
 * Merges two strings in a way that a pattern like ABABAB will be
 * the result.
 *
 * @param     string    $str1   String A
 * @param     string    $str2   String B
 * @return    string    Merged string
 */ 
function MergeBetween($str1, $str2){
 
    // Split both strings
    $str1 = str_split($str1, 1);
    $str2 = str_split($str2, 1);
 
    // Swap variables if string 1 is larger than string 2
    if (count($str1) >= count($str2))
        list($str1, $str2) = array($str2, $str1);
 
    // Append the shorter string to the longer string
    for($x=0; $x < count($str1); $x++)
        $str2[$x] .= $str1[$x];
 
    return implode('', $str2);
}

//范例演示：
print MergeBetween('abcdef', '__') . "n";
print MergeBetween('__', 'abcdef') . "n";
print MergeBetween('bb', 'aa') . "n";
print MergeBetween('aa', 'bb') . "n";
print MergeBetween('a', 'b') . "n";
 
/*
Output:
 
a_b_cdef
a_b_cdef
baba
abab
ab
*/