先给大家介绍php in array函数基本知识热热身。

定义和用法

in_array() 函数在数组中搜索给定的值。

语法
in_array(value,array,type)

参数 描述 value 必需。规定要在数组搜索的值。 array 必需。规定要搜索的数组。 type 可选。如果设置该参数为 true，则检查搜索的数据与数组的值的类型是否相同。

说明

如果给定的值 value 存在于数组 array 中则返回 true。如果第三个参数设置为 true，函数只有在元素存在于数组中且数据类型与给定值相同时才返回 true。

如果没有在数组中找到参数，函数返回 false。

注释：如果 value 参数是字符串，且 type 参数设置为 true，则搜索区分大小写。

无意中看到一段代码

<?php $y="1800";$x = array();for($j=0;$j<50000;$j++){ $x[]= "{$j}";}for($i=0;$i<30000;$i++){ if(in_array($y,$x)){ continue; } }

测试了一下

[root@dev tmp]# time php b.php
real 0m9.517s
user 0m4.486s
sys 0m0.015s

竟然需要9s

in_array是这个样子的

复制代码 代码如下:
bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

在 haystack 中搜索 needle，如果没有设置 strict 则使用宽松的比较。

needle

待搜索的值。如果 needle 是字符串，则比较是区分大小写的。

haystack

这个数组。

strict

如果第三个参数 strict 的值为 TRUE 则 in_array() 函数还会检查 needle 的类型是否和 haystack 中的相同。

那么我看一下源代码

第一步 在ext/standard/array.c 文件中

PHP_FUNCTION(in_array) { php_search_array(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0); } PHP_FUNCTION(array_search) { php_search_array(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1); }

顺便看到了array_search，原来和in_array的内部实现基本一致

其中函数的参数 在./zend.h中

#define INTERNAL_FUNCTION_PARAM_PASSTHRU ht, return_value, return_value_ptr, this_ptr, return_value_used TSRMLS_CC

第二步 在ext/standard/array.c 文件中 查看php_search_array原型

/* void php_search_array(INTERNAL_FUNCTION_PARAMETERS, int behavior) * 0 = return boolean * 1 = return key */ static void php_search_array(INTERNAL_FUNCTION_PARAMETERS, int behavior) { zval *value, *array, **entry, res; HashPosition pos; zend_bool strict = 0; ulong num_key; uint str_key_len; char *string_key; int (*is_equal_func)(zval *, zval *, zval * TSRMLS_DC) = is_equal_function; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "za|b", &value, &array, &strict) == FAILURE) { return; } if (strict) { is_equal_func = is_identical_function; } zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(array), &pos); while (zend_hash_get_current_data_ex(Z_ARRVAL_P(array), (void **)&entry, &pos) == SUCCESS) { is_equal_func(&res, value, *entry TSRMLS_CC); if (Z_LVAL(res)) { if (behavior == 0) { RETURN_TRUE; } else { switch (zend_hash_get_current_key_ex(Z_ARRVAL_P(array), &string_key, &str_key_len, &num_key, 0, &pos)) { case HASH_KEY_IS_STRING: RETURN_STRINGL(string_key, str_key_len - 1, 1); break; case HASH_KEY_IS_LONG: RETURN_LONG(num_key); break; } } } zend_hash_move_forward_ex(Z_ARRVAL_P(array), &pos); } RETURN_FALSE;}

我们发现 strict 这个值的不同有两种比较方式，看一下两个函数的不同之处

is_identical_function 检查类型是否相同

ZEND_API int is_identical_function(zval *result, zval *op1, zval *op2 TSRMLS_DC) { Z_TYPE_P(result) = IS_BOOL; if (Z_TYPE_P(op1) != Z_TYPE_P(op2)) { Z_LVAL_P(result) = 0; return SUCCESS; } switch (Z_TYPE_P(op1)) { case IS_NULL: Z_LVAL_P(result) = 1; break; case IS_BOOL: case IS_LONG: case IS_RESOURCE: Z_LVAL_P(result) = (Z_LVAL_P(op1) == Z_LVAL_P(op2)); break; case IS_DOUBLE: Z_LVAL_P(result) = (Z_DVAL_P(op1) == Z_DVAL_P(op2)); break; case IS_STRING: Z_LVAL_P(result) = ((Z_STRLEN_P(op1) == Z_STRLEN_P(op2)) && (!memcmp(Z_STRVAL_P(op1), Z_STRVAL_P(op2), Z_STRLEN_P(op1)))); break; case IS_ARRAY: Z_LVAL_P(result) = (Z_ARRVAL_P(op1) == Z_ARRVAL_P(op2) zend_hash_compare(Z_ARRVAL_P(op1), Z_ARRVAL_P(op2), (compare_func_t) hash_zval_identical_function, 1 TSRMLS_CC)==0); break; case IS_OBJECT: if (Z_OBJ_HT_P(op1) == Z_OBJ_HT_P(op2)) { Z_LVAL_P(result) = (Z_OBJ_HANDLE_P(op1) == Z_OBJ_HANDLE_P(op2)); } else { Z_LVAL_P(result) = 0; } break; default: Z_LVAL_P(result) = 0; return FAILURE; } return SUCCESS;}

is_equal_function 不检查类型是否相同，所以需要隐式转换

ZEND_API int is_equal_function(zval *result, zval *op1, zval *op2 TSRMLS_DC) { if (compare_function(result, op1, op2 TSRMLS_CC) == FAILURE) { return FAILURE; } ZVAL_BOOL(result, (Z_LVAL_P(result) == 0)); return SUCCESS;} ==》compare_functionZEND_API int compare_function(zval *result, zval *op1, zval *op2 TSRMLS_DC) { int ret; int converted = 0; zval op1_copy, op2_copy; zval *op_free; while (1) { switch (TYPE_PAIR(Z_TYPE_P(op1), Z_TYPE_P(op2))) { case TYPE_PAIR(IS_LONG, IS_LONG): ZVAL_LONG(result, Z_LVAL_P(op1)>Z_LVAL_P(op2)?1:(Z_LVAL_P(op1)<Z_LVAL_P(op2)?-1:0)); return SUCCESS; case TYPE_PAIR(IS_DOUBLE, IS_LONG): Z_DVAL_P(result) = Z_DVAL_P(op1) - (double)Z_LVAL_P(op2); ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_DVAL_P(result))); return SUCCESS; case TYPE_PAIR(IS_LONG, IS_DOUBLE): Z_DVAL_P(result) = (double)Z_LVAL_P(op1) - Z_DVAL_P(op2); ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_DVAL_P(result))); return SUCCESS; case TYPE_PAIR(IS_DOUBLE, IS_DOUBLE): if (Z_DVAL_P(op1) == Z_DVAL_P(op2)) { ZVAL_LONG(result, 0); } else { Z_DVAL_P(result) = Z_DVAL_P(op1) - Z_DVAL_P(op2); ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_DVAL_P(result))); } return SUCCESS; case TYPE_PAIR(IS_ARRAY, IS_ARRAY): zend_compare_arrays(result, op1, op2 TSRMLS_CC); return SUCCESS; case TYPE_PAIR(IS_NULL, IS_NULL): ZVAL_LONG(result, 0); return SUCCESS; case TYPE_PAIR(IS_NULL, IS_BOOL): ZVAL_LONG(result, Z_LVAL_P(op2) ? -1 : 0); return SUCCESS; case TYPE_PAIR(IS_BOOL, IS_NULL): ZVAL_LONG(result, Z_LVAL_P(op1) ? 1 : 0); return SUCCESS; case TYPE_PAIR(IS_BOOL, IS_BOOL): ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_LVAL_P(op1) - Z_LVAL_P(op2))); return SUCCESS; case TYPE_PAIR(IS_STRING, IS_STRING): zendi_smart_strcmp(result, op1, op2); return SUCCESS; case TYPE_PAIR(IS_NULL, IS_STRING): ZVAL_LONG(result, zend_binary_strcmp("", 0, Z_STRVAL_P(op2), Z_STRLEN_P(op2))); return SUCCESS; case TYPE_PAIR(IS_STRING, IS_NULL): ZVAL_LONG(result, zend_binary_strcmp(Z_STRVAL_P(op1), Z_STRLEN_P(op1), "", 0)); return SUCCESS; case TYPE_PAIR(IS_OBJECT, IS_NULL): ZVAL_LONG(result, 1); return SUCCESS; case TYPE_PAIR(IS_NULL, IS_OBJECT): ZVAL_LONG(result, -1); return SUCCESS; case TYPE_PAIR(IS_OBJECT, IS_OBJECT): if (Z_OBJ_HANDLER_P(op1,compare_objects) == Z_OBJ_HANDLER_P(op2,compare_objects)) { if (Z_OBJ_HANDLE_P(op1) == Z_OBJ_HANDLE_P(op2)) { ZVAL_LONG(result, 0); return SUCCESS; } ZVAL_LONG(result, Z_OBJ_HT_P(op1)->compare_objects(op1, op2 TSRMLS_CC)); return SUCCESS; } default: if (Z_TYPE_P(op1) == IS_OBJECT) { if (Z_OBJ_HT_P(op1)->get) { op_free = Z_OBJ_HT_P(op1)->get(op1 TSRMLS_CC); ret = compare_function(result, op_free, op2 TSRMLS_CC); zend_free_obj_get_result(op_free TSRMLS_CC); return ret; } else if (Z_TYPE_P(op2) != IS_OBJECT && Z_OBJ_HT_P(op1)->cast_object) { ALLOC_INIT_ZVAL(op_free); if (Z_OBJ_HT_P(op1)->cast_object(op1, op_free, Z_TYPE_P(op2) TSRMLS_CC) == FAILURE) { ZVAL_LONG(result, 1); zend_free_obj_get_result(op_free TSRMLS_CC); return SUCCESS; } ret = compare_function(result, op_free, op2 TSRMLS_CC); zend_free_obj_get_result(op_free TSRMLS_CC); return ret; } } if (Z_TYPE_P(op2) == IS_OBJECT) { if (Z_OBJ_HT_P(op2)->get) { op_free = Z_OBJ_HT_P(op2)->get(op2 TSRMLS_CC); ret = compare_function(result, op1, op_free TSRMLS_CC); zend_free_obj_get_result(op_free TSRMLS_CC); return ret; } else if (Z_TYPE_P(op1) != IS_OBJECT && Z_OBJ_HT_P(op2)->cast_object) { ALLOC_INIT_ZVAL(op_free); if (Z_OBJ_HT_P(op2)->cast_object(op2, op_free, Z_TYPE_P(op1) TSRMLS_CC) == FAILURE) { ZVAL_LONG(result, -1); zend_free_obj_get_result(op_free TSRMLS_CC); return SUCCESS; } ret = compare_function(result, op1, op_free TSRMLS_CC); zend_free_obj_get_result(op_free TSRMLS_CC); return ret; } else if (Z_TYPE_P(op1) == IS_OBJECT) { ZVAL_LONG(result, 1); return SUCCESS; } } if (!converted) { if (Z_TYPE_P(op1) == IS_NULL) { zendi_convert_to_boolean(op2, op2_copy, result); ZVAL_LONG(result, Z_LVAL_P(op2) ? -1 : 0); return SUCCESS; } else if (Z_TYPE_P(op2) == IS_NULL) { zendi_convert_to_boolean(op1, op1_copy, result); ZVAL_LONG(result, Z_LVAL_P(op1) ? 1 : 0); return SUCCESS; } else if (Z_TYPE_P(op1) == IS_BOOL) { zendi_convert_to_boolean(op2, op2_copy, result); ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_LVAL_P(op1) - Z_LVAL_P(op2))); return SUCCESS; } else if (Z_TYPE_P(op2) == IS_BOOL) { zendi_convert_to_boolean(op1, op1_copy, result); ZVAL_LONG(result, ZEND_NORMALIZE_BOOL(Z_LVAL_P(op1) - Z_LVAL_P(op2))); return SUCCESS; } else { zendi_convert_scalar_to_number(op1, op1_copy, result); zendi_convert_scalar_to_number(op2, op2_copy, result); converted = 1; } } else if (Z_TYPE_P(op1)==IS_ARRAY) { ZVAL_LONG(result, 1); return SUCCESS; } else if (Z_TYPE_P(op2)==IS_ARRAY) { ZVAL_LONG(result, -1); return SUCCESS; } else if (Z_TYPE_P(op1)==IS_OBJECT) { ZVAL_LONG(result, 1); return SUCCESS; } else if (Z_TYPE_P(op2)==IS_OBJECT) { ZVAL_LONG(result, -1); return SUCCESS; } else { ZVAL_LONG(result, 0); return FAILURE; } } } }