php空值替换功能 [英] php null replacement function

问题描述

Visual Basic 中有一个名为 Nz() 的函数用于应用程序.该函数检查变量是否为空，如果发现变量为空，则返回一个提供的值.

there is this function called Nz() in visual basic for application. the function checks variable nullity and returns a provided value if it finds the variable is null.

我尝试在 php 中编写相同的函数，如下所示:

i try to write the same function in php, which looks like below:

function replace_null($value, $replace) {
    if (!isset($value)) {
        return $replace;
    } else {
        return $value;
    }
}

$address = replace_null($data['address'], 'Address is not available.');

当然，如果发现$data['address']为null，php将停止执行代码并且不会调用replace_null.

of course, if $data['address'] is found null, php will stop executing the code and replace_null won't be called.

我目前正在使用三元

(isset(data['address']) ? data['address'] : 'Address is not available.');

但我认为replace_null，如果它有效，会提供一种更方便的方法.

but i think replace_null, if it works, will offer a more convenient way.

php 中是否有提供与 vba 的 Nz() 相同功能的函数?任何建议将不胜感激.

is there a function in php that provide the same functionality as vba's Nz()? any suggestion will be appreciated.

提前致谢.

推荐答案

有点迂回:如果你只用这个来检查数组成员，你可以单独传递密钥:

A bit roundabout: If you only use this to check for array members, you could pass the key separately:

function get_with_default($arr, $key, $defval)
{
  return isset($arr[$key]) ? $arr[$key] : $defval;
}

如果变量可以设置但为空(它不能，感谢@deceze)，添加另一个检查:

If the variable could be set but null ( which it cannot, thanks @deceze), add another check:

function get_and_coalesce_with_default($arr, $key, $defval)
{
  return (isset($arr[$key]) && !is_null($arr[$key]) ? $arr[$key] : $defval;
}

正如所指出的，isset() 只在非空值上成功，所以上面没有添加任何东西.不过，我们可以使用 array_key_exists 编写一个非平凡的检查:

As pointed out, isset() only succeeds on non-null values, so the above doesn't add anything. We can write a non-trivial check with array_key_exists, though:

function get_with_default_v2($arr, $key, $defval)
{
  return (array_key_exists($key, $arr) && !is_null($arr[$key]) ? $arr[$key] : $defval;
}

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