下面是另一个简单但功能强大的逻辑(Laravel框架在内部机制中也使用了这个逻辑)

/**
 * Determines if an array is associative.
 * @param  array  $array
 * @return bool
 */
function isAssoc(array $array)
{
    $keys = array_keys($array);

    return array_keys($keys) !== $keys;
}

我认为下面两个函数是最好的方法去检查'如果一个数组是结合或数字'。由于'numeric'可能只表示数字键或顺序数字键，下面列出了两个函数来检查这两种情况:

function is_indexed_array(&$arr) {
  for (reset($arr); is_int(key($arr)); next($arr));
  return is_null(key($arr));
}

function is_sequential_array(&$arr, $base = 0) {
  for (reset($arr), $base = (int) $base; key($arr) === $base++; next($arr));
  return is_null(key($arr));
}

The first function checks if each key is an integer value. The second function checks if each key is an integer value and in addition checks if all keys are sequential starting at $base, which defaults to 0 and thus can be omitted if you do not need to specify another base value. key($my_array) returns null if the read pointer is moved past the end of the array, which is what ends the for loop and makes the statement after the for loop return true if all keys were integer. If not, the loop ends prematurely because a key is of type string, and the statement after the for loop will return false. The latter function in addition adds one to $base after each compare, to be able to check if the next key is of the correct value. The strict compare makes it also check if the key is of type integer. The $base = (int) $base part in the first section of the for loop can be left out when $base is omitted or if you make sure it is only called using an integer. But since I can't be sure for everybody, I left it in. The statement is executed only once, anyway. I think these are the most efficient solutions:

Memory wise: No copying of data or key ranges. Doing an array_values or array_keys may seem shorter (less code) but keep in mind what goes on in the background once you make that call. Yes there are more (visible) statements than in some other solutions, but that is not what counts, is it? Time wise: Besides the fact that copying/extracting data and/or keys also takes time, this solution is more efficient than doing a foreach. Again a foreach may seem more efficient to some because it is shorter in notation, but in the background foreach also calls reset, key and next to do it's looping. But in addition it also calls valid to check the end condition, which is avoided here due to the combination with the integer check.

请记住，数组键只能是整数或字符串，严格的数字字符串，如“1”(但不是“01”)将被转换为整数。如果您希望数组是顺序的，这使得检查整数键成为除了计数之外唯一需要的操作。当然，如果is_indexed_array返回false，则可以将该数组视为关联数组。我说“见过”，因为事实上它们都是。

下面是另一个简单但功能强大的逻辑(Laravel框架在内部机制中也使用了这个逻辑)

/**
 * Determines if an array is associative.
 * @param  array  $array
 * @return bool
 */
function isAssoc(array $array)
{
    $keys = array_keys($array);

    return array_keys($keys) !== $keys;
}

仅仅检查数组是否有非整数键(而不是数组是否按顺序索引或零索引):

function has_string_keys(array $array) {
  return count(array_filter(array_keys($array), 'is_string')) > 0;
}

如果至少有一个字符串键，$array将被视为一个关联数组。

只是补充我的意见，我认为它应该是相当有效的基于@nonsensei的基准，以及清晰易读:

function is_associative(array $array): bool
{
    foreach ($array as $key => $value)
    {
        if (!is_string($key)) return false;
    }
    return true;
}

或者你可以用这个:

Arr::isAssoc($array)

它将检查数组是否包含任何非数字键或:

Arr:isAssoc($array, true)

检查数组是否严格顺序(包含自动生成的int键0到n-1)

使用这个库。