注意：未定义偏移：0英寸 [英] Notice: Undefined offset: 0 in

问题描述

 注意：未定义的偏移量：0 in 
 C：\xampp\htdocs\mywebsite\reddit_vote_tut\src\votes.php on line 41 
  

从这段代码：

 <？php 
 include（config.php）; 
 
函数getAllVotes（$ id）
 {
 $ votes = array（）; 
 $ q =SELECT * FROM entries WHERE id = $ id; 
 $ r = mysql_query（$ q）; 
 if（mysql_num_rows（$ r）== 1）//在表中找到$ id 
 {
 $ row = mysql_fetch_assoc（$ r）; 
 $ votes [0] = $ row ['votes_up']; 
 $ votes [1] = $ row ['votes_down']; 
} 
返回$ votes; 
} 
 
函数getEffectiveVotes（$ id）
 {
 $ votes = getAllVotes（$ id）; 
 $ effectiveVote = $ votes [0]  -  $ votes [1]; //错误发生在这里
返回$ effectiveVote; 
} 
 
 $ id = $ _POST ['id']; 
 $ action = $ _POST ['action']; 
 
 //获得当前票数
 $ cur_votes = getAllVotes（$ id）; 
 
 //好吧，现在更新票数
 
 if（$ action =='vote_up'）// vote up 
 {
 
 $ votes_up = $ cur_votes [0] +1; // AND ERROR THROWN HERE 
 
 
 $ q =更新线程SET votes_up = $ votes_up WHERE id = $ id; 
} 
 elseif（$ action =='vote_down'）
 {
 $ votes_down = $ cur_votes [1] +1; 
 $ q =更新线程SET votes_down = $ votes_down WHERE id = $ id; 
} 
 
 $ r = mysql_query（$ q）; 
 if（$ r）
 {
 $ effectiveVote = getEffectiveVotes（$ id）; 
 echo $ effectiveVote。votes; 
} 
 elseif（！$ r）//投票失败
 {
 echoFailed！; 
} 
？> 
  

解决方案

您要求 0 $ votes 。这是一个不包含该键的数组。

数组 $ votes 没有设置，所以当PHP正尝试访问数组的键 0 ，它会遇到[0]和[1]的未定义偏移量并引发该错误。

如果你有一个数组：

  $ votes = array（'1'，'2'， '3'）; 
  

我们现在可以访问：

  $票[0]; 
 $ votes [1]; 
 $ votes [2]; 
  

如果我们尝试访问：

  $票[3]; 
  

我们将会收到错误Notice：Undefined offset：3

I am getting this PHP error, what does it mean?

Notice: Undefined offset: 0 in 
C:\xampp\htdocs\mywebsite\reddit_vote_tut\src\votes.php on line 41

From this code:

<?php 
include("config.php"); 

function getAllVotes($id) 
{ 
    $votes = array(); 
    $q = "SELECT * FROM entries WHERE id = $id"; 
    $r = mysql_query($q); 
    if(mysql_num_rows($r)==1)//id found in the table 
    { 
        $row = mysql_fetch_assoc($r); 
        $votes[0] = $row['votes_up']; 
        $votes[1] = $row['votes_down']; 
    } 
    return $votes; 
} 

function getEffectiveVotes($id) 
{ 
        $votes = getAllVotes($id); 
        $effectiveVote = $votes[0] - $votes[1];    //ERROR THROWN HERE
        return $effectiveVote; 
} 

$id = $_POST['id']; 
$action = $_POST['action']; 

//get the current votes 
$cur_votes = getAllVotes($id); 

//ok, now update the votes 

if($action=='vote_up') //voting up 
{ 

    $votes_up = $cur_votes[0]+1;     //AND ERROR THROWN HERE


    $q = "UPDATE threads SET votes_up = $votes_up WHERE id = $id"; 
} 
elseif($action=='vote_down')
{ 
    $votes_down = $cur_votes[1]+1; 
    $q = "UPDATE threads SET votes_down = $votes_down WHERE id = $id"; 
} 

$r = mysql_query($q); 
if($r)
{ 
    $effectiveVote = getEffectiveVotes($id); 
    echo $effectiveVote." votes"; 
} 
elseif(!$r) //voting failed 
{ 
    echo "Failed!"; 
} 
?>

解决方案

You are asking for the value at key 0 of $votes. It is an array that does not contain that key.

The array $votes is not set, so when PHP is trying to access the key 0 of the array, it encounters an undefined offset for [0] and [1] and throws the error.

If you have an array:

$votes = array('1','2','3');

We can now access:

$votes[0];
$votes[1];
$votes[2];

If we try and access:

$votes[3];

We will get the error "Notice: Undefined offset: 3"

这篇关于注意：未定义偏移：0英寸的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！