php中拆分和组合字符串函数介绍

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

$str = "Hello world. It's a beautiful day.";
print_r (explode(" ",$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
*/