从源头再来一个。 json_encode(和bson_encode)的拟合编码。javascript数组的一致性也是如此。

function isSequential($value){
    if(is_array($value) || ($value instanceof \Countable && $value instanceof \ArrayAccess)){
        for ($i = count($value) - 1; $i >= 0; $i--) {
            if (!isset($value[$i]) && !array_key_exists($i, $value)) {
                return false;
            }
        }
        return true;
    } else {
        throw new \InvalidArgumentException(
            sprintf('Data type "%s" is not supported by method %s', gettype($value), __METHOD__)
        );
    }
}

当然，这是一个更好的选择。

<?php
$arr = array(1,2,3,4);
$isIndexed = array_values($arr) === $arr;

function is_assoc(array $array): bool
{
    foreach ($array as $iValue) {
        if (is_array($iValue)) {
            return  true;
        }
    }
    return false;

}

$d= is_assoc(["id",2,3]);

var_dump($d);

这是函数-

public function is_assoc_array($array){

    if(is_array($array) !== true){
        return false;
    }else{

        $check = json_decode(json_encode($array));

        if(is_object($check) === true){
            return true;
        }else{
            return false;
        }

    }

}

一些例子

    print_r((is_assoc_array(['one','two','three']))===true?'Yes':'No'); \\No
    print_r(is_assoc_array(['one'=>'one','two'=>'two','three'=>'three'])?'Yes':'No'); \\Yes
    print_r(is_assoc_array(['1'=>'one','2'=>'two','3'=>'three'])?'Yes':'No'); \\Yes
    print_r(is_assoc_array(['0'=>'one','1'=>'two','2'=>'three'])?'Yes':'No'); \\No

在其中一个答案中@devios1有一个类似的解决方案，但这只是使用PHP的内置json相关函数的另一种方式。我还没有检查这个解决方案在性能方面如何与其他已经在这里发布的解决方案相比。但它确实帮助我解决了这个问题。希望这能有所帮助。

我认为标量数组的定义因应用程序而异。也就是说，一些应用程序将需要更严格的定义标量数组，而一些应用程序将需要更宽松的定义。

下面我将介绍3种不同严格程度的方法。

<?php
/**
 * Since PHP stores all arrays as associative internally, there is no proper
 * definition of a scalar array.
 * 
 * As such, developers are likely to have varying definitions of scalar array,
 * based on their application needs.
 * 
 * In this file, I present 3 increasingly strict methods of determining if an
 * array is scalar.
 * 
 * @author David Farrell <DavidPFarrell@gmail.com>
 */

/**
 * isArrayWithOnlyIntKeys defines a scalar array as containing
 * only integer keys.
 * 
 * If you are explicitly setting integer keys on an array, you
 * may need this function to determine scalar-ness.
 * 
 * @param array $a
 * @return boolean
 */ 
function isArrayWithOnlyIntKeys(array $a)
{
    if (!is_array($a))
        return false;
    foreach ($a as $k => $v)
        if (!is_int($k))
            return false;
    return true;
}

/**
 * isArrayWithOnlyAscendingIntKeys defines a scalar array as
 * containing only integer keys in ascending (but not necessarily
 * sequential) order.
 * 
 * If you are performing pushes, pops, and unsets on your array,
 * you may need this function to determine scalar-ness.
 * 
 * @param array $a
 * @return boolean
 */ 
function isArrayWithOnlyAscendingIntKeys(array $a)
{
    if (!is_array($a))
        return false;
    $prev = null;
    foreach ($a as $k => $v)
    {
        if (!is_int($k) || (null !== $prev && $k <= $prev))
            return false;
        $prev = $k;
    }
    return true;
}

/**
 * isArrayWithOnlyZeroBasedSequentialIntKeys defines a scalar array
 * as containing only integer keys in sequential, ascending order,
 * starting from 0.
 * 
 * If you are only performing operations on your array that are
 * guaranteed to either maintain consistent key values, or that
 * re-base the keys for consistency, then you can use this function.
 * 
 * @param array $a
 * @return boolean
 */
function isArrayWithOnlyZeroBasedSequentialIntKeys(array $a)
{
    if (!is_array($a))
        return false;
    $i = 0;
    foreach ($a as $k => $v)
        if ($i++ !== $k)
            return false;
    return true;
}

你问了两个不完全等价的问题:

首先，如何确定数组是否只有数字键 其次，如何确定数组是否具有从0开始的连续数字键

考虑一下哪些行为是你真正需要的。(也许对你来说，这两种方法都可以。)

第一个问题(简单地检查所有键是否都是数字)由kurO船长回答得很好。

对于第二个问题(检查数组是否为0索引和顺序)，您可以使用以下函数:

function isAssoc(array $arr)
{
    if (array() === $arr) return false;
    return array_keys($arr) !== range(0, count($arr) - 1);
}

var_dump(isAssoc(['a', 'b', 'c'])); // false
var_dump(isAssoc(["0" => 'a', "1" => 'b', "2" => 'c'])); // false
var_dump(isAssoc(["1" => 'a', "0" => 'b', "2" => 'c'])); // true
var_dump(isAssoc(["a" => 'a', "b" => 'b', "c" => 'c'])); // true