php二维数组转字符串

function arr2str (KaTeX parse error: Expected '}', got 'EOF' at end of input: …{ foreach (arr as $v)
{
$v=join(",",$v); //可以用implode将一维数组转换为用逗号连接的字符串
$temp[] = $v;
}
$t="";foreach($temp as $v){
$t.={"}^{\prime }".$v."’".",";
}
$t=substr($t,0,-1);
return $t;
}