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