php array_diff 比较两个数组bug避坑 深入了解

今天实用array_diff出现的异常问题，预想的结果应该是返回 "integral_initiate"=>"0"，实际没有

先看测试代码：

$a = [
    "user_name"=>"测","see_num"=>0,"integral_initiate"=>"0"
];
$b = [
    "user_name"=>"测","see_num"=>0,"integral_initiate"=>10
];
$gf = array_diff($a,$b);
print_r($gf);

没有返回差异，纠结了好一阵子又查阅了文档看到这一句话才醒悟 

我们简化一下数组来看，通过简化数组发现只要两个数组中间都带有0的值就不会正常效验

解决方案就是换成 array_diff_assoc 对比键名与键值

------------序言--------------

虽然上面得到了想要的结果，但是本着刨根问底的思想继续研究了 一番，查了一些资料，也翻了下源码终于找到了一个合理的解释

/* {{{ proto array array_diff(array arr1, array arr2 [, array ...])
   Returns the entries of arr1 that have values which are not present in any of the others arguments. */
PHP_FUNCTION(array_diff)
{
	zval *args;
	int argc, i;
	uint32_t num;
	HashTable exclude;
	zval *value;
	zend_string *str, *tmp_str, *key;
	zend_long idx;
	zval dummy;

	if (ZEND_NUM_ARGS() < 2) {
		php_error_docref(NULL, E_WARNING, "at least 2 parameters are required, %d given", ZEND_NUM_ARGS());
		return;
	}

	ZEND_PARSE_PARAMETERS_START(1, -1)
		Z_PARAM_VARIADIC('+', args, argc)
	ZEND_PARSE_PARAMETERS_END();

	if (Z_TYPE(args[0]) != IS_ARRAY) {
		php_error_docref(NULL, E_WARNING, "Expected parameter 1 to be an array, %s given", zend_zval_type_name(&args[0]));
		RETURN_NULL();
	}

	num = zend_hash_num_elements(Z_ARRVAL(args[0]));
	if (num == 0) {
		for (i = 1; i < argc; i++) {
			if (Z_TYPE(args[i]) != IS_ARRAY) {
				php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
				RETURN_NULL();
			}
		}
		RETURN_EMPTY_ARRAY();
	} else if (num == 1) {
		int found = 0;
		zend_string *search_str, *tmp_search_str;

		value = NULL;
		ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[0]), value) {
			break;
		} ZEND_HASH_FOREACH_END();

		if (!value) {
			for (i = 1; i < argc; i++) {
				if (Z_TYPE(args[i]) != IS_ARRAY) {
					php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
					RETURN_NULL();
				}
			}
			RETURN_EMPTY_ARRAY();
		}

		search_str = zval_get_tmp_string(value, &tmp_search_str);

		for (i = 1; i < argc; i++) {
			if (Z_TYPE(args[i]) != IS_ARRAY) {
				php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
				RETURN_NULL();
			}
			if (!found) {
				ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[i]), value) {
					str = zval_get_tmp_string(value, &tmp_str);
					if (zend_string_equals(search_str, str)) {
						zend_tmp_string_release(tmp_str);
						found = 1;
						break;
					}
					zend_tmp_string_release(tmp_str);
				} ZEND_HASH_FOREACH_END();
			}
		}

		zend_tmp_string_release(tmp_search_str);

		if (found) {
			RETVAL_EMPTY_ARRAY();
		} else {
			ZVAL_COPY(return_value, &args[0]);
		}
		return;
	}

	/* count number of elements */
	num = 0;
	for (i = 1; i < argc; i++) {
		if (Z_TYPE(args[i]) != IS_ARRAY) {
			php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
			RETURN_NULL();
		}
		num += zend_hash_num_elements(Z_ARRVAL(args[i]));
	}

	if (num == 0) {
		ZVAL_COPY(return_value, &args[0]);
		return;
	}

	ZVAL_NULL(&dummy);
	/* create exclude map */
	zend_hash_init(&exclude, num, NULL, NULL, 0);
	for (i = 1; i < argc; i++) {
		ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[i]), value) {
			str = zval_get_tmp_string(value, &tmp_str);
			zend_hash_add(&exclude, str, &dummy);
			zend_tmp_string_release(tmp_str);
		} ZEND_HASH_FOREACH_END();
	}

	/* copy all elements of first array that are not in exclude set */
	array_init_size(return_value, zend_hash_num_elements(Z_ARRVAL(args[0])));
	ZEND_HASH_FOREACH_KEY_VAL_IND(Z_ARRVAL(args[0]), idx, key, value) {
		str = zval_get_tmp_string(value, &tmp_str);
		if (!zend_hash_exists(&exclude, str)) {
			if (key) {
				value = zend_hash_add_new(Z_ARRVAL_P(return_value), key, value);
			} else {
				value = zend_hash_index_add_new(Z_ARRVAL_P(return_value), idx, value);
			}
			zval_add_ref(value);
		}
		zend_tmp_string_release(tmp_str);
	} ZEND_HASH_FOREACH_END();

	zend_hash_destroy(&exclude);
}
/* }}} */

这就可以解释为什么使用array_diff 不能得到想要的结果，因为只要第一个数组中的值在第二个数组中出现过就不算差异，所以并不是bug，反过来再去看一下文档上面英文注释是这样写的

我只能说这个中文版的翻译有待提升，至此问题就到这里了

相关文档：

1、问题解答： https://stackoverflow.com/questions/4742405/array-diff-to-compare-two-associative-arrays/4742438#4742438 2、PHP 如何查看php函数源码-CSDN博客

3、源码地址 ：GitCode - 开发者的代码家园