ex_1-23.c

   1 /*
   2
   3 store state
   4
   5 store previous char
   6
   7 only check when we are not in a quoted area
   8 check current char for * or / if prev char is a / than we are in a comment
   9
  10 echo out prev char
  11
  12
  13 */
  14
  15 #include <stdio.h>
  16
  17 void advbuf(char buf[], char mrk[])
  18 {
  19         buf[0] = buf[1];
  20         mrk[0] = mrk[1];
  21
  22         //buf[1] = buf[2];
  23         //mrk[1] = mrk[2];
  24
  25         /* if buffer has comment string, continue comment by default */
  26         /* similar to carrying in math :) */
  27 }
  28
  29 int main()
  30 {
  31         char buf[2], mrk[2] = { '\0' };
  32
  33         /* mrk   c = comment  q = quote p = program */
  34
  35         char strtyp = '\0'; /* store string type */
  36         int comment = 0;
  37         /* pre-load buffer */
  38
  39         for(;;)
  40         {
  41                 advbuf(buf, mrk);
  42                 buf[1] = getchar(); // load new char at start of buffer
  43                 if(buf[1] == EOF) { return 0; } /* exit when we get to end of input */
  44
  45                 mrk[1] = 'p';
  46
  47                 /* found new quote */
  48                 if(buf[1] == '\'' || buf[1] == '"') /* found one of the quotes */
  49                 {
  50                         mrk[1] = 'q';
  51                         strtyp = buf[1];
  52                 }
  53
  54                 /* if quote is in effect, keep quoting until we find corresponding quote */
  55                 if(strtyp == '\'' || strtyp == '"')
  56                 {
  57                         if(mrk[0] == 'q')
  58                         {
  59                                 if(buf[1] == strtyp)
  60                                 {
  61                                         strtyp = '\0';
  62                                 }
  63                                 mrk[1] = 'q';
  64                         }
  65                 }
  66
  67                 if(mrk[1] == 'p' || mrk[1] == 'c')
  68                 {
  69
  70                 /* look for start of comment */
  71                 if(buf[1] == '*' || buf[1] == '/')
  72                 {
  73                         if(buf[0] == '/')
  74                         {
  75                                 mrk[0] = 'c';
  76                                 mrk[1] = 'c';
  77                                 comment = 1;
  78                         }
  79                 }
  80
  81                 /* look for end of comment */
  82                 if(comment == 1)
  83                 {
  84                         if(buf[1] == '/')
  85                                 if(buf[0] == '*' || buf[0] == '/')
  86                                 {
  87                                         mrk[0] = 'c';
  88                                         mrk[1] = 'c';
  89                                         comment = 0;
  90                                 }
  91                         mrk[1] = 'c';
  92                 }
  93
  94                 }
  95                 //printf("%c%c", buf[0], buf[1]);
  96                 //printf("->%c%c\n", mrk[0], mrk[1]);
  97
  98                 /* based on current state print output */
  99                 if(mrk[0] == 'p' || mrk[0] == 'q') { putchar(buf[0]); }
 100         }
 101
 102         printf("This is a comment in a quote /* comment here */ just ignore it.\n");
 103
 104         return 0;
 105 }