Thread: [C] remove comments

He said that he wasn't including C99 single line comments, only block comments.

&& has higher priority than ||, so if you don't remove it, then you need to put paren around the all the or statements to make it work right.

Originally Posted by Aksel

It has improved a lot. It does not handle this contrived situation:

Code:

// Look, I am being clever, using line-continuation to turn a single-line comment\
into a multi-line comment.

GCC will warn you about such multi-line comments if you use "-Wall".

If you use -Wall, GCC will also warn you about

Code:

    if(state == normal || 
    state == squote || state == squote2 || state == squote3 || state == squote4 || state == squote_escape ||
    state == dquote || state == dquote_escape || state == octal || state == hexa && 
    state!=comment_exit2)

I think it is safe to remove the last part "&& state != comment_exit" which is a given.

Whats -Wall used for? Why?

I tried writing it into parameters of my compilers, it still doesnt recognizes the case with comments you mentioned.

Originally Posted by Tool

Whats -Wall used for? Why?

Warning Options - Using the GNU Compiler Collection (GCC)

This enables all the warnings about constructions that some users consider questionable, and that are easy to avoid (or modify to prevent the warning), even in conjunction with macros. This also enables some language-specific warnings described in C++ Dialect Options and Objective-C and Objective-C++ Dialect Options.

and

Note that some warning flags are not implied by -Wall. Some of them warn about constructions that users generally do not consider questionable, but which occasionally you might wish to check for; others warn about constructions that are necessary or hard to avoid in some cases, and there is no simple way to modify the code to suppress the warning. Some of them are enabled by -Wextra but many of them must be enabled individually.

[edit]
Using -Wall will often draw my attention to potential bugs.

I tried writing it into parameters of my compilers, it still doesnt recognizes the case with comments you mentioned.

"-Wall" is specific to GCC, your compiler may have a similar option though. Which compiler is it?

Anyways, i shortened the code alot, the only reason i had squote states so much last time was the syntax checker from which i took most of the code. It dealt with the states aswell, just much more detail.
So here it is, the most shortened version:

Code:

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

int main(int argc, char *argv[])
{
    
     int c;
     enum states { normal,
                   squote, squote_escape,
                   comment_entry, comment, comment_exit, comment_exit2, comment2,
                   dquote, dquote_escape };
     int state = normal; 
     int second; /* stores the tmp character after slash */
     int flag=0; /* if 1, puts the character stored in second */
     
  

       while((c=getchar())!=EOF)
      {
         if(state == normal && c=='\'') { state = squote; }
         else if(state == normal && c=='"') { state = dquote; }
         else if(state == normal && c=='/')
         { 
              second=getchar(); 
              if(second=='*') 
              {
                 ungetc(c, stdin); 
                 state = comment; 
              }
              
              else if(second=='/') 
              {
                 ungetc(c, stdin);
                 state = comment2; 
              }
              
              else if(second=='\'') {state = squote; }
              else if(second=='"') { state = dquote; }
              
              else flag=1;
         }    
      
         else if(state == comment && c=='*') { state = comment_exit; }
         else if(state == comment) {}
         
         else if(state == comment_exit && c=='*') {}
         else if(state == comment_exit && c=='/') { putchar(' '); state = comment_exit2; }
         else if(state == comment_exit) { state = comment; }
         
         else if(state == comment2 && c=='\n') { state = normal; }
         else if(state == comment2) { }         
         
         else if(state == squote && c=='\\') { state = squote_escape; }
         else if(state == squote && (c=='\'' || c=='\n')) { state = normal; }
         else if(state == squote) { }
         
         else if(state == squote_escape && c=='\n') { state = normal; }
         else if(state == squote_escape) { state = squote; }
         
         else if(state == dquote && c=='\n') { state = normal; }
         else if(state == dquote && c=='"') { state = normal; }
         else if(state == dquote && c=='\\') { state = dquote_escape; }
         else if(state == dquote) { }
         
         else if(state ==dquote_escape) { state = dquote; }
         
         if((state == normal || state == squote || state == squote_escape || state == dquote || state == dquote_escape) && state!=comment_exit2) 
         putchar(c); 
         
         if(state==comment_exit2) { state = normal; }     
         if(flag==1) { flag=0; putchar(second); }
         
      }
     
   
    printf("Press any key to continue");   
    getchar();	
    return 0;
}

insert

Code:

/*  comment line */
//comment line
/*
comment line
*/
#include"stdio.h"

void main(int argc,char *argv[])
{
	char ch,ch1,ch2;
	FILE *fp,*fp1;
	fp=fopen("filename","r");/*in place of "filename" u can put a command line argument file argv[1]*/ 
	fp1=fopen("temp","w");
	if(!fp || !fp1)
	{
		printf("cannot open file ");
		exit(0);
	}


	while((ch=getc(fp)) != EOF)
	{
		
		if(ch=='/')
			if( ((ch1=getc(fp))!= EOF) && (ch1=='*') )
				do{
					if(ch1=='*' && ((ch2=getc(fp))!= EOF) && ch2=='/') 
						break;
					continue;
				}while((ch1=getc(fp))!= EOF);
			else
				if(ch1=='/')
					do{
						if( ((ch2=getc(fp)) != EOF) && ch2=='\n')
							break;
						continue;
					}while((ch1=getc(fp))!= EOF);
				else
					{
						putc(ch,fp1);
						putc(ch1,fp1);
					}
		else
			putc(ch,fp1);

	}
	
	
	fclose(fp);
	fclose(fp1);
	remove("filename");
	rename("temp","filename");
	
}