php分割合并两个字符串的函数实例

/**
 * 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
*/