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Quest: page 34

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Write a program to remove all comments from a C program. Don't forget to handle quoted string and character constants properly. C comments doesn't nest.

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• check for single line comment '//' => print line until that occurence;
• check multiline comment '/* */' => print the line after that;
• ignore quote strings "//" and "/* */"

preprocess comments

#include <stdio.h>
#include <stdlib.h>

#define MAX 1024
#define IN 1
#define OUT 0

/*
         THIS SHOULD BE REMOVED
         TEST COMMENT FROM MATTHIAS
                                                                        THE END
   IS SOMEWHERE HERE IN THE TEXT CAPITAL
                                                                        */

int gl(char s[], int lim) {
  int c;
  int lastchar = 0;
  int i;
  for (i = 0; (c = getchar()) != EOF && c != '\n'; i++) {
    if (i < lim - 1) {
      s[i] = c;
    }
  }
  if (c == '\n') {
    s[i] = '\n';
    i++;
  }
  s[i] = '\0';
  return i;
}

int main() {
  // THESE kinds needs to be removed
  // "single line comment"
  /*
  multi
  */
  char s[MAX];
  int len;
  int single = OUT;
  int multi = OUT;
  int notThisLine = 0;
  char *q = "//";    // NOTE should be printed
  char *p = "/* */"; // Note should be printed
  char x= '\"'; // singlequotet doublequote checker
  while ((len = gl(s, MAX)) > 0) {
    // check single line comment with sliding window approach
    notThisLine = 0; // nasty comment should be removed after
    for (int i = 0; i < len; i++) {
      // check double quotet string
      if (s[i] == '\"' && s[i - 1] != '\\') {
        while (i < len) {
          i++;
          if (s[i] == '\"' && s[i - 1] != '\\') {
            break;
          }
        }
        continue;
      }
      if (s[i] == '/' && i + 1 < len && s[i + 1] == '/') {
        for (int j = 0; j < i; j++) {
          printf("%c", s[j]);
        }
        printf("\n");
        single = IN;
        break;
      }
      // check multi start
      if (s[i] == '/' && i + 1 < len && s[i + 1] == '*') {
        multi = IN;
      }
      // check multi end
      if (s[i] == '*' && i + 1 < len && s[i + 1] == '/') {
        multi = OUT;
        notThisLine = 1;
        break;
      }
    }
    if (single) {
      single = OUT;
      continue;
    }
    // check  multi
    if (multi == OUT && notThisLine == 0) {
      printf("%s", s);
    }
  }
}