unix cat implementation problem

[ocg]

Hello,

my cat implementation is sort of working but when i put multiple options like -ne, it doesnt work properly.

it should print something like this

1 text$
2 txt$
3 abc$
....

mine prints like this

1 text
2 txt
3 abc
text$
txt$
abc$

my main.c

while ((c = getopt (argc, argv, "ne")) != -1) {
                        
                        
                        for(int i = 2; i < argc; i++) {
                                
                                file = fopen ( argv[i], "r" );
                                
                                if (file == NULL){
                                        
                                        puts ( "\nNo such file or directory\n" );
                                }
                                
                                
                                
                                
                        } 
                        
                        
                        //  printf("%c", optopt);
                        
                        switch (c) {
                                        
                                case 'n':
                              
                                        optLineNums(argc, argv, file, count, chars);
                                        
                                        break;
                                        
                                        
                                        
                                case 'e':
                                     
                                        flagE = 1;
                                        optEndOfLine(file, chars, argc, argv);
                                        
                                        
                                        break;
                                        
                                case '?':
                                        fprintf (stderr, "Unknown option character '-%c'. Use -e or -n options\n", optopt);
                                        break;
                                default:
                                        abort ();
                        }
                        
                }

cat.c

void optLineNums(int argc, char *argv[], FILE *file, int count, char chars) {
        int charCount = 0;
        
        while ( argc ) {
                
                
                chars = fgetc (file);
                
                
                if ( chars == EOF )
                        break;
                
                else {
                        if(charCount == 0){
                                printf("     %i\t",count);
                                charCount++;
                        }
                        
                        if (chars == '\n'){
                                count++;
                                printf("\n"); 
                                printf("     %i\t",count);   
                                
                        } else
                                fputc ( chars, stdout );
                }
                
                
                
        }
}




void optEndOfLine(FILE *file, char chars, int argc, char *argv[]) {
        
        
        while ( argc ) {
                
                chars = fgetc (file);
                
                if (chars == '\n')
                        chars = '$';
                
                if ( chars == EOF )
                        break;
                else
                        fputc ( chars, stdout );
                
                if (chars == '$')
                        puts("");
                
                
        }
        
}

Thanks in advance

[Salem]

Why are you opening files in the middle of your getopt loop?

Typically, your getopt loop would set variables, so that when you actually get around to displaying a file, it would be something like
displayfile( argv[i], showLineNumbers, showEndOfLineMarkers );

[ocg]

Why are you opening files in the middle of your getopt loop?

Typically, your getopt loop would set variables, so that when you actually get around to displaying a file, it would be something like
displayfile( argv[i], showLineNumbers, showEndOfLineMarkers );

thank you for the response.. i was opening files in my methods i shared here but I though my problem was coming from opening files twice.. so I decided to put it somewhere else..

Anyway.. I am not quite sure how your suggestion can be done any easier suggestion would be much better

[Salem]

Well your main would be

int main ( int argc, char *argv[] ) {
  while ( getopt() ) {
    // scan args, and set flags
  }
  for ( i = 1 ; i < argc ; i++ ) {
    // process each arg[i] as a file, 
    // using the options you discovered
  }
}

[ocg]

Well your main would be

int main ( int argc, char *argv[] ) {
  while ( getopt() ) {
    // scan args, and set flags
  }
  for ( i = 1 ; i < argc ; i++ ) {
    // process each arg[i] as a file, 
    // using the options you discovered
  }
}

Thanks again for your help..

Is it something like this?

	      for(int i = 2; i < argc; i++) {
                        
                        file = fopen ( argv[i], "r" );
		    
		    
                        if (file == NULL){
                                
			  puts ( "\nNo such file or directory\n" );
		    }
		    
		   
                }
	      
	      //for (int x = 1; x<optind; x++){
		    if (flagN == 1)
			  optLineNums(argc, argv, file, count, chars);   
		    if (flagE == 1)
			  optEndOfLine(file, chars, argc, argv); 
	      //}

[Salem]

Something like it, yes.
But what you're lacking is something for when both flagN and flagE are both set.

Look at the similarities between optLineNums() and optEndOfLine()
Both are doing substantially the same thing (print a file to screen).

If you passed flagN and flagE to a common function, you could display line numbers and/or end of line markers using the SAME code.

[itCbitC]

    for (int i = 2; i < argc; i++) {
        file = fopen ( argv[i], "r" );
            if (file == NULL) {
                puts ( "\nNo such file or directory\n" );
            }
        }

Do you think the above loop will work if options are separated "-n" and "-e" instead of grouped together "-ne"?
So as suggested, focus on processing the command line options before moving onto processing the input files.

[ocg]

Something like it, yes.
But what you're lacking is something for when both flagN and flagE are both set.

Look at the similarities between optLineNums() and optEndOfLine()
Both are doing substantially the same thing (print a file to screen).

If you passed flagN and flagE to a common function, you could display line numbers and/or end of line markers using the SAME code.

are you saying that I should create a new method for when both flags are set?

[ocg]

Do you think the above loop will work if options are separated "-n" and "-e" instead of grouped together "-ne"?
So as suggested, focus on processing the command line options before moving onto processing the input files.

well, that error checking is for testing only... will be fixed...

[Salem]

> are you saying that I should create a new method for when both flags are set?
You can if you want.
But don't you also need a function for when no flags are set?

That's a total of 4 nearly identical functions all doing essentially the same thing (cat) with slightly different output effects.

Think about this.
If you added a 3rd flag (say expand tabs to spaces), would you add just one parameter to one function (my way), or copy/paste the 4 functions you have (making 8 functions) just to cover all the possibly permutations of the flags you have.