我希望在默认情况下选中一个复选框， - I want a checkbox to be checked by default,

I want a checkbox to be checked by default,

我什么时候更新我的学期？默认情况下，会选中复选框？

<select name="semester">
  <option value="">Select Semester</option>
  <option value="1">Semester 1</option>
  <option value="2">Semester 2</option>
  <option value="3">Semester 3</option>
</select>

您可以使用selected属性。

<select name="semester">
     <option value="">Select Semester</option>
     <option value="1" selected="selected">Semester 1</option>
     <option value="2">Semester 2</option>
     <option value="3">Semester 3</option>
</select>

请尝试此

<select name="semester">
            <option value="">Select Semester</option>
            <option value="1" <?php if($data['semester']==1){echo 'selected';}?>>Semester 1</option>
            <option value="2" <?php if($data['semester']==2){echo 'selected';}?>>Semester 2</option>
            <option value="3" <?php if($data['semester']==3){echo 'selected';}?>>Semester 3</option>
</select>

如果您想选择semester 2，请点击此处：

HTML:

<select name="semester">
  <option value="">Select Semester</option>
  <option value="1">Semester 1</option>
  <option value="2" selected>Semester 2</option>
  <option value="3">Semester 3</option>
</select>

Jquery：

$("select option").each(function(){
  if ($(this).text() == "Semester 2")
    $(this).attr("selected","selected");
});

是的，这是可能的。你必须在<option> 中使用selected

<select name="semester">
        <option value="">Select Semester</option>
        <option value="1" selected>Semester 1</option>
        <option value="2">Semester 2</option>
        <option value="3">Semester 3</option>
</select>

DEMO

<option value="1" <?= ($value=='1')?'selected':"" ?>>Semester 1</option>
<option value="2" <?= ($value=='2')?'selected':"" ?>>Semester 2</option>
<option value="3" <?= ($value=='3')?'selected':"" ?>>Semester 3</option>

您可以从数据库或会话中获取值，

我们确实需要您的特定PHP代码来提供帮助，但也许这个通用示例将向您展示当您拥有数据和所需值时如何做到这一点：

<?php
    //Your array of data
    $myData = array(
        '1' => 'Semester 1',
        '2' => 'Semester 2',
        '3' => 'Semester 3');
    //The value you want to be selected
    $myValue = "2";
?>
<select name="semester">
    <option value="">Select Semester</option>
        <?php
            foreach($myData as $key => $value){
                echo ('<option value="'.$key.'"' );
                if( $myValue == $key){
                    echo( ' selected="selected" ');
                }
                echo ('>'.$value.'</option');
                echo "'n";
            }
        ?>
</select>