Question

如何解决问题注意：

未定义的变量：b in   C：\ wamp64 \ www \ MyFolder \ version1.1 \ fms \ build \ english \ equipment.php on   第904行

警告：in_array（）期望参数2为数组，null中给定为null   C：\ wamp64 \ www \ MyFolder \ version1.1 \ fms \ build \ english \ equipment.php on   第904行

<div class="form-group">
    <label class="custom-control custom-checkbox" style="margin-left: 10px; margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Tv" class="custom-control-input" 
<?php 
if (isset($_POST["equipment_id"]))
    {
    $id = $_POST['equipment_id'];
    $query = mysqli_query("SELECT * FROM equipment WHERE id='$id'");
    $row = mysqli_fetch_array($query);
    $a = $row["equipment"];
    $b = explode(",", $a);
    print_r($b);
    }

if (in_array("Tv", $b))
    {
    echo "checked";
    }

?> >
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/tv-icon.png" width="25px" height="25px">
        <span class="custom-control-description">TVs</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Phone" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/phone-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Phone</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Fan" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/fan-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Fan</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Mirror" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/mirror-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Mirrors</span>
    </label>
</div>

Answer 1

根据我的评论，将in_array()条件置于isset()条件下。未定义变量的原因是$b仅存在于isset()条件中。因此，当您离开isset()条件并尝试访问$b时，会抛出错误

if (isset()){
#your isset() code

    if(in_array()){
#in_array() code

    } #place in_array() inside isset()
} # end isset()

作为提示，请务必养成在使用前定义变量的习惯..最后请使用预备语句进行查询..

Answer 2

php代码的顶部请声明数组$ b

 $b=array();

在您的代码中编写if条件，如果不满足则$ b变量未定义。所以在条件之前请声明数组。

$b=array();
if (isset($_POST["equipment_id"])) {
//your code        
}

谢谢

使用explode php

2 个答案: