数组合并

1.关联数组
$arr1=array('a'=>'PHP');
$arr2=array('a'=>'JAVA');
//如果键名为字符，且键名相同，array_merge()后面数组元素值会覆盖前面数组元素值
print_r(array_merge($arr1,$arr2));//Array ( [a] => JAVA )
//如果键名为字符，且键名相同，数组相加会将最先出现的值作为结果
print_r($arr1+$arr2);//Array ( [a] => PHP )

2.索引数组
$arr1=array("C","PHP");
$arr2=array("JAVA","PHP");
//如果键名为数字，array_merge()不会进行覆盖
print_r(array_merge($arr1,$arr2));//Array ( [0] => C [1] => PHP [2] => JAVA [3] => PHP )
//如果键名为数组，数组相加会将最先出现的值作为结果，后面键名相同的会被抛弃
print_r($arr1+$arr2);//Array ( [0] => C [1] => PHP )