How to use PHP language to implement the city ABC arrangement function

When developing a website or application, it is often necessary to arrange city names in alphabetical order, which makes it easier for users to find and browse. This article will introduce how to use PHP language to implement the city ABC arrangement function.

1. Obtain city data

First, you need to obtain city data. You can get the city list from a third-party data source, or you can define the city array yourself in the program. The following example code is to manually define the city array:

$cities = array(
    '北京', '上海', '广州', '深圳', '杭州', '南京', '成都', 
    '重庆', '长沙', '武汉', '西安', '天津', '青岛', '大连', 
    '沈阳', '郑州', '石家庄', '哈尔滨', '济南', '南昌', '福州',
    '厦门', '昆明', '太原', '兰州'
);

2. Implement the city ABC arrangement

Next, you need to implement the city ABC arrangement function through the PHP function. The following sample code is an implementation method:

function cityABC($data) {
    $result = array();

    foreach ($data as $k => $v) {
        $first = mb_substr($v, 0, 1, 'utf-8');
        $result[$first][] = $v;
    }
    
    ksort($result);
    
    return $result;
}

In the above code, the function cityABC() passes in a city array and returns a multi-dimensional array sorted by the first letter of the city. The mb_substr() function is used in the function to obtain the first letter of each city name, and the cities are grouped according to the first letter. Finally, the ksort() function is used to sort the grouped city array in alphabetical order.

3. Display the city ABC ranking results

Finally, display the city ABC ranking results on the page. The following example code is a display method:

$city_ABC = cityABC($cities);
foreach ($city_ABC as $key => $value) {
    echo '<hr>';
    echo '<h2 id="key">' . $key . '</h2>';
    echo '

';     foreach ($value as $val) {         echo '
• ' . $val . '
';     }     echo '

'; }

In the above code, first call the cityABC() function to sort the city array by first letter, then use the foreach() function to traverse the multi-dimensional array and format the result in HTML output to the page.

The complete code is as follows:

$cities = array(
    '北京', '上海', '广州', '深圳', '杭州', '南京', '成都', 
    '重庆', '长沙', '武汉', '西安', '天津', '青岛', '大连', 
    '沈阳', '郑州', '石家庄', '哈尔滨', '济南', '南昌', '福州',
    '厦门', '昆明', '太原', '兰州'
);

function cityABC($data) {
    $result = array();

    foreach ($data as $k => $v) {
        $first = mb_substr($v, 0, 1, 'utf-8');
        $result[$first][] = $v;
    }
    
    ksort($result);
    
    return $result;
}

$city_ABC = cityABC($cities);

foreach ($city_ABC as $key => $value) {
    echo '
';
    echo '
' . $key . '
';
    echo '

';     foreach ($value as $val) {         echo '
• ' . $val . '
';     }     echo '

'; }

Conclusion

The above example code implements the city ABC arrangement function, which can facilitate users to search and browse cities. Of course, this code can also be optimized and improved according to actual needs.

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