在PHP中，在数组上使用if(isset）时，节点不再存在 - Node no longer exists using if (isset) on an array in PHP

是否可以对数组中的项使用if-iset？

示例：

if (isset($cityWeatherRssUrls[0])

这样做时，我收到以下警告。

警告：get_temperature（）[function.get-temperature]：节点不再存在于第51行上的C:''examplep''htdocs''Twinz''includes''getWeather.php中

第51行开始于我的getWeather.php脚本中函数get_temperature（SimpleXMLElement$xml）的//Pull temperature注释之后。

以下包含的所有相关脚本和功能

cityConfig.php-用于向yahoo的天气XML声明所有城市和相应的URL。

// Define arrays // 
$cities = array();
$cityWeatherRssUrls = array(); 
// Feed URL's //
$yahooWeather = 'http://weather.yahooapis.com/forecastrss?p=';
// City 1 //
$city = 'London';
$cityWeatherRssUrl = $yahooWeather . $cityWeatherFeedCode . '&u=c';
array_push($cities, $city);
array_push($cityWeatherRssUrls, $cityWeatherRssUrl);

getWeather.php-包含解析XML标记内容和显示内容的函数

function get_current_weather($weatherRssUrl) {
    // Get XML data from source
    if (isset($weatherRssUrl)) {
        $feed = $weatherRssUrl;
    } else {
        echo 'Feed not found.  Check URL';
    }
    checkFeedExists($feed);
    $xml = new SimpleXmlElement($feed);
    $weather = get_temperature($xml);
return $weather;
}
function get_temperature(SimpleXMLElement $xml) {
    // Pull temperature from XML 
    $weather['temp'] = $xml->channel->item->children('yweather', TRUE)->condition->attributes()->temp;
    echo round($weather['temp']) . "&deg;C" . "<br />";
return $temp;
}
//Display City Content //
function displayCityContent($cityWeatherRssUrls, $columnSubheading) {
    if (isset($cityWeatherRssUrls)) {
        echo get_current_weather($cityWeatherRssUrls);
        echo $columnSubheading;
        echo get_forecast_weather($cityWeatherRssUrls);
        echo '<br />';
    } else {
        content_unavailable();
    }
}

threeColumnContainer.php-用于在html列中显示天气内容

<ul class="columns">
    <li class="col1">
        <h3><?php
        if (isset($column1Heading)) {
        echo $column1Heading;
        }
        ?></h3>
            <p>
                <?php
                if (isset($cityWeatherRssUrls[0]) && ($currentPage == 1)) {
                    echo displayCityContent($cityWeatherRssUrls[0], $columnSubheading);

我可以确认$cityWeatherRssUrls[0]包含伦敦的天气url，因为如果我递增数组@cityWeatherRssUrls[1]，我会收到一条消息，说找不到提要。

有什么想法吗？

提前感谢

您的代码中缺少了一些关键概念，但希望以下内容能帮助您修复代码。。。

<?php
function get_feed($feed_url)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $feed_url);
    curl_setopt($ch, CURLOPT_FRESH_CONNECT, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $rss = curl_exec($ch);
    curl_close($ch);
    return $rss;
}
function get_weather_feed_xml($feed_url = null)
{
    $feed = get_feed($feed_url);
    return new SimpleXmlElement($feed);
}
function get_temperature($feed_url)
{
    if(stripos($feed_url, 'yahooapis') !== false)
    {
        return get_temperature_yahoo($feed_url);
    }
    return false;
}
function get_temperature_yahoo($feed_url)
{
    if(($xml = get_weather_feed_xml($feed_url)) !== false)
    {
        return (float)$xml->channel->item->children('yweather', true)->condition->attributes()->temp;
    }
    return false;
}
function get_city_temperature($city_name, $city_WOEID, $feeds)
{
    $results = array();
    foreach($feeds as $feed_name => $feed_url)
    {
        $feed_url = str_replace(array('{WOEID}', '{NAME}'), array($city_WOEID, $city_name), $feed_url);
        $results[$feed_name] = get_temperature($feed_url);
    }
    return $results;
}
function get_cities_temperature($cities, $feeds)
{
    $results = array();
    foreach($cities as $city_name => $city_WOEID)
    {
        $results[$city_name] = get_city_temperature($city_name, $city_WOEID, $feeds);
    }
    return $results;
}

// -------------------------------
$cities = array(
    'London'        => 44418, 
    'Los Angeles'   => 2442047, 
    'Sydney'        => 1105779, 
);
$feeds = array(
    'Yahoo' => 'http://weather.yahooapis.com/forecastrss?u=c&w={WOEID}', 
);
$check = get_cities_temperature($cities, $feeds);
echo '<pre>';
print_r($check);
echo '</pre>';