php verification array cannot be empty

In PHP, we can use the isset() function to check whether a variable is defined or assigned a value. For arrays, we can use empty() function or count() function to check if the array is empty.

The empty() function checks all elements in the array and returns true if the array is empty or the values ​​of all elements are considered "false values". "False values" include false, empty string, 0, empty array, etc.

The following is an example:

$array1 = array();
if (empty($array1)) {
  echo "数组为空";
} else {
  echo "数组不为空";
}

// 输出结果为：数组为空

count() function will return the number of elements in the array. If there are no elements in the array, 0 is returned. Therefore, we can use count() function to check if the array is empty.

Here is an example:

$array2 = array(1, 2, 3);
if (count($array2) == 0) {
  echo "数组为空";
} else {
  echo "数组不为空";
}

// 输出结果为：数组不为空

Also, if we want to check whether a multi-dimensional array is empty, we need to use a recursive function to traverse the entire array. The following is an example function:

function is_empty_array($array) {
  if (!is_array($array)) {
    return false;
  }

  foreach ($array as $value) {
    if (is_array($value)) {
      if (!is_empty_array($value)) {
        return false;
      }
    }
    else {
      if (!empty($value)) {
        return false;
      }
    }
  }

  return true;
}

This function will recursively traverse each element in the multi-dimensional array and return a Boolean value indicating whether the array is empty.

Here is a usage example:

$array3 = array(
  1,
  array(
    2,
    array()
  ),
  ''
);

if (is_empty_array($array3)) {
  echo "数组为空";
} else {
  echo "数组不为空";
}

// 输出结果为：数组为空

In short, we can use the empty() function, count() function and recursive function to check whether the array is empty. In actual development, we can choose the appropriate method according to the specific situation.

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