Question

我有一个用C语言编写的程序，它可以将正则表达式应用于字符串。

但是，它仅适用于正则表达式

\\w ('\\' means single '\' in string).

\\w+ \\s+ \\s or [^\\s]+  
did not take effect.

似乎，

"^","[","]","+"

未得到该计划的认可。

该程序的运行格式如下：

./program {regular expression}

然后输入一行字符串，程序会将正则表达式应用于字符串并给出结果。

我检查程序并没有发现任何错误。

/* the function get a substring from a string */
static char* substr(const char*str,unsigned start, unsigned end)
{
  unsigned n = end - start;
  static char stbuf[256];
  strncpy(stbuf, str + start, n);
  stbuf[n] = 0;
  return stbuf;
}

/* the main program */
int main(int argc, char** argv)
{
  char * pattern;
  int x, z, lno = 0, cflags = 0;
  char ebuf[128], lbuf[256];
  regex_t reg;
  regmatch_t pm[10];
  const size_t nmatch = 10;
  /* complie regular expression*/
  pattern = argv[1];
  z = regcomp(&reg, pattern, cflags);
  if (z != 0){
  regerror(z, &reg, ebuf, sizeof(ebuf));
   fprintf(stderr, "%s: pattern '%s' \n",ebuf, pattern);
   return 1;
  }
/* get the line of input string */
  while(fgets(lbuf, sizeof(lbuf), stdin))
  {
    ++lno;
    if ((z=strlen(lbuf)) > 0 && lbuf[z-1] == '\n')
    lbuf[z - 1] = 0;
    /* match input line with regular expression */
    z = regexec(&reg, lbuf, nmatch, pm, 0);
    if (z == REG_NOMATCH){printf("not match\n,pattern is %s\n",pattern);     
continue;}
    else if (z != 0) {
      regerror(z, &reg, ebuf, sizeof(ebuf));
      fprintf(stderr, "%s: regcom('%s')\n", ebuf, lbuf);
      return 2;
    }  printf(" $%d='%s'\n", x, substr(lbuf, pm[x].rm_so, pm[x].rm_eo));};
    }
  }
  /*releasing the compiled regular expresion struct*/
  regfree(&reg);
 return 0;
}
    /* Deal with output result  */
    for (x = 0; x < nmatch && pm[x].rm_so != -1; ++ x)
    {
      if (!x) {printf("%04d: %s\n", lno, lbuf);
       printf(" pattern is %s",pattern);
       printf(" $%d='%s'\n", x, substr(lbuf, pm[x].rm_so, pm[x].rm_eo));};
    }
  }
  /*releasing the compiled regular expresion struct*/
  regfree(&reg);
  return 0;
}

正则表达式中的“+”，“[”，“]”在Linux C中没有生效

0 个答案: