为什么我无法使用它的密钥访问数组元素？

Question

I have a bellow php while and for loop.

In while loop it's storing $ch_for data in $ch_for array.

Using print_r this array is showing these value :

Array ( [ch7] => Seven [ch8] => Eight )

And trying to access this array data in for loop using this line :

echo $ch_for["ch{$x}"]; 

But it's showing an error message : Illegal string offset 'ch7' in ...

While and For Loop

$ch_for     = array();
$ch_name    = array();

while ( $fetchChannel =  mysqli_fetch_array($getChannel) ) {
    $ch_id      = (int) $fetchChannel['ch_id'];
    $ch_for[$fetchChannel['ch_name']]   = htmlspecialchars($fetchChannel['ch_for']);
    $ch_name[]  = htmlspecialchars($fetchChannel['ch_name']);
}


for ($x=1; $x<=12; $x++) {
    if(  in_array('ch'.$x, $ch_name)) {
        $sel = 'checked = "checked" ';
        echo $ch_for["ch{$x}"];
    } else {
        $sel = '';
        $ch_for = '';
    }
    ?>

    <div class="checkbox form-inline">
        <label><input <?php echo $sel; ?> type="checkbox" name="ch_name[]" value="ch<?php echo $x; ?>">CH<?php echo $x; ?></label>
        <input type="text" name="ch_for[]" value="<?php echo $ch_for; ?>" placeholder="Channel details" class="form-control ch_for">
    </div>                                    
    <?php
}

Result of var_dump(array_keys($ch_for));

array(2) {
  [0]=>
  string(3) "ch7"
  [1]=>
  string(3) "ch8"
}

Answer 1

You're overwriting $ch_for in your else-branch since the first key is ch7, hence the first loop (ch1 is not in $ch_name and thus triggers the else) overwrites $ch_for.