php内置函数分析之strpos()

 1 PHP_FUNCTION(strpos) 2 { 3 ????zval *needle; 4 ????zend_string *haystack; 5 ????char *found = NULL; 6 ????char ?needle_char[2]; 7 ????zend_long ?offset = 0; // 搜索位置默认0 8 ?9 ????ZEND_PARSE_PARAMETERS_START(2, 3)10 ????????Z_PARAM_STR(haystack)11 ????????Z_PARAM_ZVAL(needle)12 ????????Z_PARAM_OPTIONAL13 ????????Z_PARAM_LONG(offset)14 ????ZEND_PARSE_PARAMETERS_END();15 16 ????/* 如果搜索起始位置offset<0, 则转换一下 */17 ????if (offset < 0) {18 ????????offset += (zend_long)ZSTR_LEN(haystack);19 ????}20 ????/* 如果转换之后 offset<0 或 offset大于(待查找字符串的长度)，则待查找字符串中根本就没有这个位置*/21 ????if (offset < 0 || (size_t)offset > ZSTR_LEN(haystack)) {22 ????????php_error_docref(NULL, E_WARNING, "Offset not contained in string");23 ????????RETURN_FALSE;24 ????}25 26 ????/* 搜索 */27 ????if (Z_TYPE_P(needle) == IS_STRING) { // needle是字符串28 ????????/* needle长度为0，则报错 */29 ????????if (!Z_STRLEN_P(needle)) {30 ????????????php_error_docref(NULL, E_WARNING, "Empty needle");31 ????????????RETURN_FALSE;32 ????????}33 ????????/* 具体的搜索实现 */34 ????????found = (char*)php_memnstr(ZSTR_VAL(haystack) + offset,35 ????????????????????????????Z_STRVAL_P(needle),36 ????????????????????????????Z_STRLEN_P(needle),37 ????????????????????????????ZSTR_VAL(haystack) + ZSTR_LEN(haystack));38 ????} else {39 ????????if (php_needle_char(needle, needle_char) != SUCCESS) {40 ????????????RETURN_FALSE;41 ????????}42 ????????needle_char[1] = 0;43 44 ????????found = (char*)php_memnstr(ZSTR_VAL(haystack) + offset,45 ????????????????????????????needle_char,46 ????????????????????????????1,47 ????????????????????????????ZSTR_VAL(haystack) + ZSTR_LEN(haystack));48 ????}49 50 ????if (found) {51 ????????RETURN_LONG(found - ZSTR_VAL(haystack));52 ????} else {53 ????????RETURN_FALSE;54 ????}55 }