php函数式编程简单示例

// 函数式编程$users = array(  array('id' => 1, 'name' => 'abc1', 'age' => 29, '性别' => '男'),  array('id' => 2, 'name' => 'abc2', 'age' => 21, '性别' => '女'),  array('id' => 3, 'name' => 'abc3', 'age' => 23, '性别' => '男'),  array('id' => 4, 'name' => 'abc4', 'age' => 25, '性别' => '女'),  array('id' => 5, 'name' => 'abc5', 'age' => 20, '性别' => '女'),  array('id' => 6, 'name' => 'abc6', 'age' => 24, '性别' => '男'),  array('id' => 7, 'name' => 'abc7', 'age' => 28, '性别' => '女'),  array('id' => 8, 'name' => 'abc8', 'age' => 27, '性别' => '男'),);//获取性别为女的用户$arrayFilter = array_filter($users, function($item){  return $item['性别'] == '女' ;});// 不影响原数组，返回一个新数组$arrayMap = array_map(function($item){  return array(    'id' => $item['id'],    'name' => $item['name'],    'age' => $item['age'],    'gender' => $item['性别'] == '男' ? 'male' : 'female',  );}, $users);// 修改原数组，对年龄+10处理，同时新增索引gender，返回值 1 或 0array_walk($users, function(&$item, $index){  $item['gender'] = $item['性别'] == '男' ? 'male' : 'female';  if ($index % 2 == 0) {    $item['age'] += 10;  }});//array_reduce(array $input , callable $function [,$initial = NULL ]) 用回调函数迭代地将数组简化为单一的值// 求最大年龄的用户,返回最大年龄用户信息$arrayReduce = array_reduce($users, function($init, $val){  return $init['age'] > $val['age'] ? $init : $val;}, array('age' => 0));// 求平均年龄$avgAge = array_reduce($users, function($init, $item){  return $init + $item['age'];}, 0) / count($users);/* * array_reduce 的内部实现方式function array_reduce($data, $callback, $initial) {  foreach ($data as $index => $val) {    $initial = $callback($initial, $val);  }  return $initial;}*///用array_map和array_mutisort来排序 //利用array_map获取要依据排序的数组,(匿名函数 create_function($args, return $val))//$arrField = array_map(create_function('$item', 'return $item["age"];'), $users); 【不推荐】$arrField = array_map(function($item){  return $item['age'];}, $users);//利用array_mutisort来进行年龄从大到小排序$arrSort = array_multisort($arrField, SORT_DESC, $users);

//闭包实现计数器function counts() {  $a = 1;  // 闭包,引用变量$a  return function() use(&$a) {    return $a++;  };}$countFunc = counts();echo $countFunc(); // 1echo $countFunc(); // 2echo $countFunc(); // 3echo $countFunc(); // 4