Question

这就是我到目前为止所拥有的：

foreach ($users as $user) {
            if (!array_keys($usersPerCity, $user->city)){
                $usersPerCity[]=[$user->city => 1];
            }else{
                $usersPerCity[$user->city] = ($usersPerCity[$user->city] + 1);
            }
        }

我的+1的作用为0，它只是创建城市=> 1而无需添加。我将如何汇总已经存在的城市？

Answer 1

您以正确的方式在<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <display-name>Archetype Created Web Application</display-name> </web-app>中拥有了它。另外，这不是else的目的，您是说array_keys吗？无论如何，只要使用array_key_exists，就可以增加isset：

++

从PHP 7.0开始，只需从对象数组中提取foreach ($users as $user) { if (!isset($usersPerCity[$user->city])){ $usersPerCity[$user->city] = 1; } else { //$usersPerCity[$user->city] = ($usersPerCity[$user->city] + 1); $usersPerCity[$user->city]++; } }并计算值：

city

PHP检查assoc数组的键，如果存在，则将值提高1

1 个答案: