C++ program to remove C/C++ style comments, while keep string content intact and line numbers of code unchnaged...

#include <string.h> #include <stdio.h> #include <sys/types.h> #include <stdlib.h> #include <stdarg.h> #include <string> #include <iostream> #include <vector> #include <string> int my_fgets(std::string &str, FILE *fp, unsigned char to_remove_comments) {     // read one line from file. if end of file return 0 otherwise return 1     int ret=1;     static unsigned char prev_linebreak;     unsigned char ch;     str.clear();     while(1) {         ch = fgetc(fp);         if (feof(fp)) {             prev_linebreak='\0';             if (str.empty())                 ret=0;             break;         }         if (ch=='\r') {             prev_linebreak='\r';             break;         }         if (ch=='\n') {             if (prev_linebreak=='\r') {                 prev_linebreak='\0';                 continue;             } else {                 prev_linebreak='\n';                 break;             }         }         str+=ch;     }     if (to_remove_comments)     {         std::string tmpstr=str;                  static enum IN_COMMENT_T {             IN_COMMENT_NOT,             IN_COMMENT_WAIT_FOR_STAR_SLASH,             IN_COMMENT_DOUBLE_QUOTE,         } in_comment = IN_COMMENT_NOT;         const char *p, *p_limit, *p_start;                  str.clear();         p_start = tmpstr.c_str();         p_limit = p_start + tmpstr.length();                  for(p=p_start; p<p_limit; p++) {             switch(in_comment) {             case IN_COMMENT_NOT:                 if (strncmp(p, "//", 2)==0) {                     p=p_limit-1;                     continue;                 } else if (strncmp(p, "/*", 2)==0) {                     in_comment=IN_COMMENT_WAIT_FOR_STAR_SLASH;                     p+=(sizeof("/*")-1)-1;                 } else if (*p=='"') {                     // avoid case like '"'                     if (p==p_start || *(p-1)!='\'')                         in_comment=IN_COMMENT_DOUBLE_QUOTE;                 }                 break;             case IN_COMMENT_WAIT_FOR_STAR_SLASH:                 if (strncmp(p, "*/", 2)==0) {                     in_comment=IN_COMMENT_NOT;                     p+=sizeof("*/")-1;                 }                 break;             case IN_COMMENT_DOUBLE_QUOTE:                 if (*p=='"') {                     // need to count how many '\' in the front. If it is even number then end of quote!                     const char *q;                     for(q=p-1; q>=p_start && *q=='\\'; q--);                     if ((p-q)&1) {                         // note (p-q)-1 is the number of '\\' before '"'.                         // if ((p-q)-1) is odd, the " is escaped.                         // if ((p-q)-1) is even, the " is a real close quotoation.                         in_comment=IN_COMMENT_NOT;                     }                 }                 break;             default:                 break;             }                      if (in_comment==IN_COMMENT_NOT || in_comment==IN_COMMENT_DOUBLE_QUOTE)                 str = str+*p;         }                  if (ret==0)             in_comment = IN_COMMENT_NOT;     }     return ret; } int  main(int argc, char **argv) {     FILE *fp=NULL;     std::string str;     if (argc!=2) {         fprintf(stderr, "remove C style comment in a text file and show in stdout\n");         fprintf(stderr, "usage: %s file\n", argv[0]);         goto MAIN_ERROR;     }     fp=fopen(argv[1], "rb");     if (fp==NULL)  {         fprintf(stderr, "error in open %s\n", argv[1]);         goto MAIN_ERROR;     }     while(my_fgets(str, fp, 1))         fprintf(stderr, "%s\n", str.c_str());                      MAIN_ERROR:     if (fp)         fclose(fp);     return 0; }