Use PHP to write a function about getting weather conditions for a specified number of days. The function section is normal, but when it is added to the for loop, there is no display or error. How to solve it?

Question

Reference materials:
Sina weather api description
Brief description The last parameter in the url, day=0, represents today, if equal to 1, it represents the next day, and so on, but The maximum value is 3.

Code Target:

Jinhua Weather

Today xx-xx-xx Sunday x Sunny to cloudy during the day xxxx

Week x Sunny to cloudy during the day xxxx at night (Day 2)

Sunday x Sunny to cloudy during the day and xxxx at night (Day 3)

Sunday x Sunny to cloudy during the day and xxxx at night (Day 4)

<?php 
function get_weather($k=3){
 $arr = array('星期日','星期一','星期二','星期三','星期四','星期五','星期六','星期日','星期一','星期二');
 $week=date('w');
 $arrfeng=array('无风','软风','轻风','微风','和风','轻劲风','强风','疾风','大风','烈风','狂风','暴风','台风','风王之王');
 $winfo='金华天气';
for ($i=0; $i>$k ; $i++) { 
          $url='http://php.weather.sina.com.cn/xml.php?city=%bd%f0%bb%aa&password=DJOYnieT8234jlsK&day='.$i;
          $ch=curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
          $output = curl_exec($ch);
curl_close($ch);
          $outobj=simplexml_load_string($output);
          $a=$outobj->Weather;
//为了方便拼接字符串
          $b=$a->status1;//天气情况1代表白天
          $c=$a->status2;//天气情况2代表晚上
          $d=$a->direction1;//白天风向
          $e=$a->direction2;//晚上风向
          $dd=$a->power1;//白天风级数
          $ee=$a->power2;//晚上风级数
if($c=="")$c=$b;//解决 当晚上和白天 天气一样时 变量ee值为空
             //$winfo='金华天气'
              $winfo.= $arr[$week+$k].'白天'.$b.$d.$arrfeng[intval($dd)].'晚上'.$c.$e.$arrfeng[intval($ee)].'\n';
          }
return $winfo;
}
$str=get_weather(3);
echo $str;
?>

But if you don’t add a for loop, you can achieve it with a solid line by executing the function 4 times. code show as below

<?php 
function get_weather($i){
 $arr = array('星期日','星期一','星期二','星期三','星期四','星期五','星期六','星期日','星期一','星期二');
 $week=date('w');
 $arrfeng=array('无风','软风','轻风','微风','和风','轻劲风','强风','疾风','大风','烈风','狂风','暴风','台风','风王之王');
 $winfo='  ';
          $url='http://php.weather.sina.com.cn/xml.php?city=%bd%f0%bb%aa&password=DJOYnieT8234jlsK&day='.$i;
          $ch=curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
          $output = curl_exec($ch);
curl_close($ch);
          $outobj=simplexml_load_string($output);
          $a=$outobj->Weather;
//为了方便拼接字符串
          $b=$a->status1;//天气情况1代表白天
          $c=$a->status2;//天气情况2代表晚上
          $d=$a->direction1;//白天风向
          $e=$a->direction2;//晚上风向
          $dd=$a->power1;//白天风级数
          $ee=$a->power2;//晚上风级数
if($c=="")$c=$b;//解决 当晚上和白天 天气一样时 变量ee值为空
             //$winfo='金华天气';原本在这里（每循环一次就被清空一次这是错误的）
              $winfo.= $arr[$week+$i].'白天'.$b.$d.$arrfeng[intval($dd)].'晚上'.$c.$e.$arrfeng[intval($ee)].'\n';
          
return $winfo;
}
$str0=get_weather(0);
$str1=get_weather(1);
$str2=get_weather(2);
$str3=get_weather(3);
echo '金华天气'.$str0.$str1.$str2.$str3;
?>

The output is as follows:

Jinhua Weather Friday Thundershowers during the day, east wind calm, cloudy at night, east wind calm n Saturday, thundershowers during the day, east wind calm, evening cloudy east wind, calm n Sunday, cloudy during the day, east wind calm, evening clear, east wind calm, n Monday clear during the day, east wind calm, clear at night No wind n

Answer 1

The judgment condition of your for loop is wrong. How is it possible to write $i>$k, and then let $i++.

<?php 
function get_weather($k=3){
 $arr = array('星期日','星期一','星期二','星期三','星期四','星期五','星期六','星期日','星期一','星期二');
 $week=date('w');
 $arrfeng=array('无风','软风','轻风','微风','和风','轻劲风','强风','疾风','大风','烈风','狂风','暴风','台风','风王之王');
 $winfo='金华天气';
for ($i=0; $i<=$k ; $i++) { 
          $url='http://php.weather.sina.com.cn/xml.php?city=%bd%f0%bb%aa&password=DJOYnieT8234jlsK&day='.$i;
          $ch=curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
          $output = curl_exec($ch);
curl_close($ch);
          $outobj=simplexml_load_string($output);
          $a=$outobj->Weather;
//为了方便拼接字符串
          $b=$a->status1;//天气情况1代表白天
          $c=$a->status2;//天气情况2代表晚上
          $d=$a->direction1;//白天风向
          $e=$a->direction2;//晚上风向
          $dd=$a->power1;//白天风级数
          $ee=$a->power2;//晚上风级数
if($c=="")$c=$b;//解决 当晚上和白天 天气一样时 变量ee值为空
             //$winfo='金华天气'
              $winfo.= $arr[$week+$k].'白天'.$b.$d.$arrfeng[intval($dd)].'晚上'.$c.$e.$arrfeng[intval($ee)].'\n';
          }
return $winfo;
}
$str=get_weather(3);
echo $str;
?>

Answer 2

The for loop condition is written wrong, it should be $i<=$k