PHP determines the character type. PHP inserts new characters at the specified position in the string.

　Because the project uses the DataTable table to load background data and needs to connect the table to query the policy status selected by the virtual machine, so I thought of taking out the content of the policy table first to form a '< ;/option>[n options]' string, spell its policy value into a string like 'value="1"' when traversing the virtual machine list, and then use explode() and the implode() function to form a new string and return it to the front desk to achieve the selected state.

<span><span> 1    </span><span>$option</span> = '<select>'<span>;
</span><span> 2    </span><span> 3    </span><span>//</span><span> 取出所有策略</span><span> 4    </span><span>$sla_query</span> = <span>$this</span>->db->select('sla_id, name')->get('sla'<span>);
</span><span> 5</span><span>$sla_res</span> = <span>$sla_query</span>-><span>result_array();
</span><span> 6</span><span>if</span> (!<span>empty</span>(<span>$sla_res</span><span>)) {
</span><span> 7</span><span>$option</span> .= '<option value="0">未保护</option>'<span>;
</span><span> 8</span><span>foreach</span> (<span>$sla_res</span><span>as</span><span>$k1</span> => <span>$v1</span><span>) {
</span><span> 9</span><span>$option</span> .= '<option value="' . <span>$v1</span>['sla_id'] . '">' . <span>$v1</span>['name'] . '</option>'<span>;
</span><span>10</span><span>            }
</span><span>11</span><span>$option</span> .= '</select>'<span>;
</span><span>12</span><span>13</span>         } <span>else</span><span> {
</span><span>14</span><span>$option</span> .= '<option value="0">未保护</option></select>'<span>;
</span><span>15</span><span>        }
</span><span>16</span><span>17</span><span>18    </span><span>//</span><span> 选中默认的保护策略</span><span>19    </span><span>$vm_query</span> = <span>$this</span>->db->select('sla_id')->where('vm_id', <span>$</span>vm_id)->get('task_vm', 1<span>);
</span><span>20</span><span>$vm_res</span> = <span>$vm_query</span>-><span>row_array();
</span><span>21    </span><span>if</span> (<span>is_null</span>(<span>$vm_res</span>['sla_id'])) <span>$res</span>['sla_id'] = 0<span>;
</span><span>22    </span><span>$selected</span> = 'value="' . <span>$vm_res</span>['sla_id'] . '"'<span>;
</span><span>23    </span><span>$new_str_arr</span> = <span>explode</span>(<span>$selected</span>, <span>$option</span><span>);
</span><span>24</span><span>$new_option</span> = <span>implode</span>(" {<span>$selected</span>} selected", <span>$new_str_arr</span>);</span>

The above introduces PHP to determine the character type. PHP inserts new characters at the specified position in the string, including the content of PHP to determine the character type. I hope it will be helpful to friends who are interested in PHP tutorials.