PHP 源码探秘-为甚么 trim 会致使乱码

运转以下代码：

$tag = "互联网产物、";$text = rtrim($tag, "、");print_r($text);

运转，咱们能够觉得会获得的成果是 互联网产物 ，现实成果是 互联网产 。为甚么会如许呢？

道理

trim 函数文档

string trim ( string $str [, string $character_mask = " 	x0B" ] )

该函数不是多字节函数，也便是说，汉字如许的多字节字符，会拿其头或尾的单字节来和前面的 $character_mask 对应的char数组停止婚配，若是在前面的数组中，则删掉，持续婚配。比方：

echo ltrim("bcdf","abc"); // df

以上面的 demo 中的函数 string_print_char 所示：

、 由 0xe3 0x80 0x81 三字节构成，

品 由 0xe5 0x93 0x81 三字节构成。

以是在履行 rtrim 的时辰，经由过程字节比对，会将 0x81 去掉，致使了最初呈现了乱码。

源码精简版演示

检查 PHP7 的源码，而后提炼出上面的小 demo ，便利大师一路进修，实在PHP源码的进修并不难，天天前进一点点。

//// main.c// trim//// Created by 周梦康 on 2017/10/18.// Copyright  2017年 周梦康. All rights reserved.//#include <stdio.h>#include <stdlib.h>#include <string.h>void string_print_char(char *str);void php_charmask(unsigned char *input, size_t len, char *mask);char *ltrim(char *str,char *character_mask);char *rtrim(char *str,char *character_mask);int main(int argc, char const *argv[]){ printf("%s",ltrim("bcdf","abc"));  string_print_char("品"); // e5 93 81 string_print_char("、"); // e3 80 81  printf("%s",rtrim("互联网产物、","、"));   return 0;}char *ltrim(char *str,char *character_mask){ char *res; char mask[256]; register size_t i; int trimmed = 0;  size_t len = strlen(str);  php_charmask((unsigned char*)character_mask, strlen(character_mask), mask);  for (i = 0; i < len; i++) { if (mask[(unsigned char)str[i]]) { trimmed++; } else { break; } }  len -= trimmed; str += trimmed;  res = (char *) malloc(sizeof(char) * (len+1)); memcpy(res,str,len);  return res;}char *rtrim(char *str,char *character_mask){ char *res; char mask[256]; register size_t i;  size_t len = strlen(str);  php_charmask((unsigned char*)character_mask, strlen(character_mask), mask);  if (len > 0) { i = len - 1; do { if (mask[(unsigned char)str[i]]) { len--; } else { break; } } while (i-- != 0); }  res = (char *) malloc(sizeof(char) * (len+1)); memcpy(res,str,len);  return res;}void string_print_char(char *str){ unsigned long l = strlen(str);  for (int i=0; i < l; i++) { printf("%02hhx	",str[i]); }  printf("");}void php_charmask(unsigned char *input, size_t len, char *mask){ unsigned char *end; unsigned char c;  memset(mask, 0, 256);  for (end = input+len; input < end; input++) { c = *input; mask[c]= 1; }}

PHP7 相干源码

PHP_FUNCTION(trim){ php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 3);}PHP_FUNCTION(rtrim){ php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 2);}PHP_FUNCTION(ltrim){ php_do_trim(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);}static void php_do_trim(INTERNAL_FUNCTION_PARAMETERS, int mode){ zend_string *str; zend_string *what = NULL; ZEND_PARSE_PARAMETERS_START(1, 2) Z_PARAM_STR(str) Z_PARAM_OPTIONAL Z_PARAM_STR(what) ZEND_PARSE_PARAMETERS_END(); ZVAL_STR(return_value, php_trim(str, (what ? ZSTR_VAL(what) : NULL), (what ? ZSTR_LEN(what) : 0), mode));}PHPAPI zend_string *php_trim(zend_string *str, char *what, size_t what_len, int mode){ const char *c = ZSTR_VAL(str); size_t len = ZSTR_LEN(str); register size_t i; size_t trimmed = 0; char mask[256]; if (what) { if (what_len == 1) { char p = *what; if (mode & 1) { for (i = 0; i < len; i++) { if (c[i] == p) { trimmed++; } else { break; } } len -= trimmed; c += trimmed; } if (mode & 2) { if (len > 0) { i = len  1; do { if (c[i] == p) { len--; } else { break; } } while (i-- != 0); } } } else { php_charmask((unsigned char*)what, what_len, mask); if (mode & 1) { for (i = 0; i < len; i++) { if (mask[(unsigned char)c[i]]) { trimmed++; } else { break; } } len -= trimmed; c += trimmed; } if (mode & 2) { if (len > 0) { i = len - 1; do { if (mask[(unsigned char)c[i]]) { len--; } else { break; } } while (i-- != 0); } } } } else { if (mode & 1) { for (i = 0; i < len; i++) { if ((unsigned char)c[i] <= " " && (c[i] == " " || c[i] == "" || c[i] == "" || c[i] == "	" || c[i] == "v" || c[i] == "")) { trimmed++; } else { break; } } len -= trimmed; c += trimmed; } if (mode & 2) { if (len > 0) { i = len - 1; do { if ((unsigned char)c[i] <= " " && (c[i] == " " || c[i] == "" || c[i] == "" || c[i] == "	" || c[i] == "v" || c[i] == "")) { len--; } else { break; } } while (i-- != 0); } } } if (ZSTR_LEN(str) == len) { return zend_string_copy(str); } else { return zend_string_init(c, len, 0); }}/* {{{ php_charmask * Fills a 256-byte bytemask with input. You can specify a range like "a..z", * it needs to be incrementing. * Returns: FAILURE/SUCCESS whether the input was correct (i.e. no range errors) */static inline int php_charmask(unsigned char *input, size_t len, char *mask){ unsigned char *end; unsigned char c; int result = SUCCESS; memset(mask, 0, 256); for (end = input+len; input < end; input++) { c=*input; if ((input+3 < end) && input[1] == "." && input[2] == "." && input[3] >= c) { memset(mask+c, 1, input[3] - c + 1); input+=3; } else if ((input+1 < end) && input[0] == "." && input[1] == ".") { /* Error, try to be as helpful as possible: (a range ending/starting with "." won"t be captured here) */ if (end-len >= input) { /* there was no "left" char */ php_error_docref(NULL, E_WARNING, "Invalid ".."-range, no character to the left of "..""); result = FAILURE; continue; } if (input+2 >= end) { /* there is no "right" char */ php_error_docref(NULL, E_WARNING, "Invalid ".."-range, no character to the right of "..""); result = FAILURE; continue; } if (input[-1] > input[2]) { /* wrong order */ php_error_docref(NULL, E_WARNING, "Invalid ".."-range, ".."-range needs to be incrementing"); result = FAILURE; continue; } /* FIXME: better error (a..b..c is the only left possibility?) */ php_error_docref(NULL, E_WARNING, "Invalid ".."-range"); result = FAILURE; continue; } else { mask[c]=1; } } return result;}/* }}} */