Question

如果不存在import sys PY3K = sys.version_info >= (3, 0) if PY3K: source = sys.stdin.buffer else: # Python 2 on Windows opens sys.stdin in text mode, and # binary data that read from it becomes corrupted on \r\n if sys.platform == "win32": # set sys.stdin to binary mode import os, msvcrt msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY) source = sys.stdin b = source.read()，则$category未定义。那么如果只有它存在，我怎么能通过$category。

$category

Answer 1

您只需将Method中的hi hello world! abc def ghijkl mno pqr!初始化为空值即可。因此，即使您的$category未能conditional logic，我们也会有一个空值来回落.....

override $category

<强>可替换地：

<?php


    public function receive(Request $request) {
        $category   = null;     //<== INITIALIZE THE $category VARIABLE TO NULL.
        if ($request->ajax()) {
            if ($id = $request->id) {
                $receive = User::where(['id' => $id])->first();
                if (isset($receive->category->name)) {
                    $category = $receive->category->name;
                }

                die( json_encode([
                    'status'   => TRUE,
                    'receive'  => $receive,
                    'category' => $category
                ]));
            }
        }
    }

Answer 2

试试这个......

$category = isset($_GET['category']) ? $_GET['category'] : '';

未定义的变量（如果不存在）

2 个答案: