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：

1. $a = [
2. "user_name"=>"测","see_num"=>0,"integral_initiate"=>"0"
3. ];
4. $b = [
5. "user_name"=>"测","see_num"=>0,"integral_initiate"=>10
6. ];
7. $gf = array_diff($a,$b);
8. print_r($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

1. /* {{{ proto array array_diff(array arr1, array arr2 [, array ...])
2. Returns the entries of arr1 that have values which are not present in any of the others arguments. */
3. PHP_FUNCTION(array_diff)
4. {
5. zval *args;
6. int argc, i;
7. uint32_t num;
8. HashTable exclude;
9. zval *value;
10. zend_string *str, *tmp_str, *key;
11. zend_long idx;
12. zval dummy;
14. if (ZEND_NUM_ARGS() < 2) {
15. php_error_docref(NULL, E_WARNING, "at least 2 parameters are required, %d given", ZEND_NUM_ARGS());
16. return;
17. }
19. ZEND_PARSE_PARAMETERS_START(1, -1)
20. Z_PARAM_VARIADIC('+', args, argc)
21. ZEND_PARSE_PARAMETERS_END();
23. if (Z_TYPE(args[0]) != IS_ARRAY) {
24. php_error_docref(NULL, E_WARNING, "Expected parameter 1 to be an array, %s given", zend_zval_type_name(&args[0]));
25. RETURN_NULL();
26. }
28. num = zend_hash_num_elements(Z_ARRVAL(args[0]));
29. if (num == 0) {
30. for (i = 1; i < argc; i++) {
31. if (Z_TYPE(args[i]) != IS_ARRAY) {
32. php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
33. RETURN_NULL();
34. }
35. }
36. RETURN_EMPTY_ARRAY();
37. } else if (num == 1) {
38. int found = 0;
39. zend_string *search_str, *tmp_search_str;
41. value = NULL;
42. ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[0]), value) {
43. break;
44. } ZEND_HASH_FOREACH_END();
46. if (!value) {
47. for (i = 1; i < argc; i++) {
48. if (Z_TYPE(args[i]) != IS_ARRAY) {
49. php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
50. RETURN_NULL();
51. }
52. }
53. RETURN_EMPTY_ARRAY();
54. }
56. search_str = zval_get_tmp_string(value, &tmp_search_str);
58. for (i = 1; i < argc; i++) {
59. if (Z_TYPE(args[i]) != IS_ARRAY) {
60. php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
61. RETURN_NULL();
62. }
63. if (!found) {
64. ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[i]), value) {
65. str = zval_get_tmp_string(value, &tmp_str);
66. if (zend_string_equals(search_str, str)) {
67. zend_tmp_string_release(tmp_str);
68. found = 1;
69. break;
70. }
71. zend_tmp_string_release(tmp_str);
72. } ZEND_HASH_FOREACH_END();
73. }
74. }
76. zend_tmp_string_release(tmp_search_str);
78. if (found) {
79. RETVAL_EMPTY_ARRAY();
80. } else {
81. ZVAL_COPY(return_value, &args[0]);
82. }
83. return;
84. }
86. /* count number of elements */
87. num = 0;
88. for (i = 1; i < argc; i++) {
89. if (Z_TYPE(args[i]) != IS_ARRAY) {
90. php_error_docref(NULL, E_WARNING, "Expected parameter %d to be an array, %s given", i + 1, zend_zval_type_name(&args[i]));
91. RETURN_NULL();
92. }
93. num += zend_hash_num_elements(Z_ARRVAL(args[i]));
94. }
96. if (num == 0) {
97. ZVAL_COPY(return_value, &args[0]);
98. return;
99. }
101. ZVAL_NULL(&dummy);
102. /* create exclude map */
103. zend_hash_init(&exclude, num, NULL, NULL, 0);
104. for (i = 1; i < argc; i++) {
105. ZEND_HASH_FOREACH_VAL_IND(Z_ARRVAL(args[i]), value) {
106. str = zval_get_tmp_string(value, &tmp_str);
107. zend_hash_add(&exclude, str, &dummy);
108. zend_tmp_string_release(tmp_str);
109. } ZEND_HASH_FOREACH_END();
110. }
112. /* copy all elements of first array that are not in exclude set */
113. array_init_size(return_value, zend_hash_num_elements(Z_ARRVAL(args[0])));
114. ZEND_HASH_FOREACH_KEY_VAL_IND(Z_ARRVAL(args[0]), idx, key, value) {
115. str = zval_get_tmp_string(value, &tmp_str);
116. if (!zend_hash_exists(&exclude, str)) {
117. if (key) {
118. value = zend_hash_add_new(Z_ARRVAL_P(return_value), key, value);
119. } else {
120. value = zend_hash_index_add_new(Z_ARRVAL_P(return_value), idx, value);
121. }
122. zval_add_ref(value);
123. }
124. zend_tmp_string_release(tmp_str);
125. } ZEND_HASH_FOREACH_END();
127. zend_hash_destroy(&exclude);
128. }
129. /* }}} */

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