请问strtok为什么不能继续输出子串？
华为OD题，简单题
题目2 标题 火星文计算
描述 已知火星人使用的运算符为#、$，其与地球人的等价公式如下：
x#y = 4x+3y+2
x$y = 2*x+y+3
1、其中x,y 是无符号整数
2、地球人公式按C语言规则计算
3、火星人公式中，#的优先级高于$，相同的运算符，按从左到右的顺序计算。
现有一段火星人的字符报文，请你来翻译并计算结果
输入描述
火星人字符串表达式（结尾不带回车换行）
输入的字符串说明：字符串为仅由无符号整数和操作符（#，$）组成的计算表达式。例如：123#4$5#67$78
1、用例保证字符串中，操作数与操作符之间没有任何分隔符
2、用例保证操作数取值范围为32位无符号整数
3、保证输入以及计算结果不会出现整数溢出
4、保证输入的字符串为合法的求值报文，例如123#4$5#67$78
5、保证不会出现非法的求值报文，例如类似这样字符串：
#4$5 //缺少操作数
4$5# //缺少操作数
4#$5 //缺少操作数
4 $5 //有空格
3+4-5*6/7 //有其他操作符
12345678987654321$54321 //32位整数计算溢出
输出描述
根据输入的火星人字符串输出计算结果（结尾不带回车换行）
示例1
输入
7#6$5#12
输出
157
说明
示例：
7#6$5#12
=（47+36+2）$5#12
=48$5#12
=48$(45+312+2)
=48$58
=2*48+58+3
=157
我的问题描述:想用strtok分优先级先按照$分段然后逐段再解决，却发现无法成功输出下一个子串，但我没有用p操作而是复制了内存，不知道为什么无法继续分段？
C:\Program Files (x86)\Microsoft SDK\src\crt\strtok.c
/***
*strtok.c - tokenize a string with given delimiters
*
* Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines strtok() - breaks string into series of token
* via repeated calls.
*
*******************************************************************************/
#include <cruntime.h>
#include <string.h>
#ifdef _MT
#include <mtdll.h>
#endif /* _MT */
/***
*char *strtok(string, control) - tokenize string with delimiter in control
*
*Purpose:
* strtok considers the string to consist of a sequence of zero or more
* text tokens separated by spans of one or more control chars. the first
* call, with string specified, returns a pointer to the first char of the
* first token, and will write a null char into string immediately
* following the returned token. subsequent calls with zero for the first
* argument (string) will work thru the string until no tokens remain. the
* control string may be different from call to call. when no tokens remain
* in string a NULL pointer is returned. remember the control chars with a
* bit map, one bit per ascii char. the null char is always a control char.
*
*Entry:
* char *string - string to tokenize, or NULL to get next token
* char *control - string of characters to use as delimiters
*
*Exit:
* returns pointer to first token in string, or if string
* was NULL, to next token
* returns NULL when no more tokens remain.
*
*Uses:
*
*Exceptions:
*
*******************************************************************************/
char * __cdecl strtok (
char * string,
const char * control
)
{
unsigned char *str;
const unsigned char *ctrl = control;
unsigned char map[32];
int count;
#ifdef _MT
_ptiddata ptd = _getptd();
#else /* _MT */
static char *nextoken;
#endif /* _MT */
/* Clear control map */
for (count = 0; count < 32; count++)
map[count] = 0;
/* Set bits in delimiter table */
do {
map[*ctrl >> 3] |= (1 << (*ctrl & 7));
} while (*ctrl++);
/* Initialize str. If string is NULL, set str to the saved
* pointer (i.e., continue breaking tokens out of the string
* from the last strtok call) */
if (string)
str = string;
else
#ifdef _MT
str = ptd->_token;
#else /* _MT */
str = nextoken;
#endif /* _MT */
/* Find beginning of token (skip over leading delimiters). Note that
* there is no token iff this loop sets str to point to the terminal
* null (*str == '\0') */
while ( (map[*str >> 3] & (1 << (*str & 7))) && *str )
str++;
string = str;
/* Find the end of the token. If it is not the end of the string,
* put a null there. */
for ( ; *str ; str++ )
if ( map[*str >> 3] & (1 << (*str & 7)) ) {
*str++ = '\0';
break;
}
/* Update nextoken (or the corresponding field in the per-thread data
* structure */
#ifdef _MT
ptd->_token = str;
#else /* _MT */
nextoken = str;
#endif /* _MT */
/* Determine if a token has been found. */
if ( string == str )
return NULL;
else
return string;
}
可以查看手册：c语言-strtok() 中的内容