如何判断每组数组里有多少个正数和负数?
$arr=array(array('3','-1','4','2','-2'),array('-3','-1','-4','-12','-2','21','13','-16'),array('-5','-8','4','2'));
------解决方案--------------------
php code$arr=array( array('3','-1','4','2','-2'), array('-3','-1','-4','-12','-2','21','13','-16'), array('-5','-8','4','2'));foreach($arr as $k=>$a) { $n = count(array_keys(array_map('sign',$a), -1)); $r[$k] = array('+' => count($a) - $n, '-' => $n);}print_r($r);function sign($n) { return $n/abs($n);}