Thread: reading in a text file containing hex values

Well, your code works okay on my end with the sample file you gave. It's difficult to troubleshoot something you can't reproduce.

I'm not sure if scanf actually reads and advances past the whitespace? I'm not very familiar with it.
Other suggestions might include... when you open the file, specify "r", not "rt". And no magic numbers... You can just use sizeof(buffer) instead.

>I'm not sure if scanf actually reads and advances past the whitespace?
Except for %c, %[, and %n, leading whitespace is skipped.

Works for me,
using this input file:

Code:

1C 3
A4 7
23 C8
1F 98

And this code:

Code:

#include <stdio.h>

void display(int a, int v)  ;

int main()
{
	FILE *file_ptr;
	int address[2014], value[2014], i, j;
	
	file_ptr = fopen("/Users/toddburch/Documents/hexdata.txt","rt");

	if (file_ptr == NULL) 
	{
		printf("file cannot be opened or does not exist.\n");
		return -1 ;
	} 
	
	printf("settings file found\n");
	
	for (i = 0 ; i < sizeof(address) ; i++ )
	{
		fscanf(file_ptr,"&#37;0x",&address[i]);
		if (feof(file_ptr)) break ; 
		
		fscanf(file_ptr,"%0x",&value[i]);
		if (feof(file_ptr)) break ; 
	}
			
	printf("total number of values read %d\n",i);
	
	for (j=0 ; j<i ; j++ ) 
	{
		display( address[j], value[j] );
	}

	fclose(file_ptr);
	return 0;
}

void display(int a,int v)
{
	printf("%x	%x\n", a,v);
}

and I get this output:

Code:

[Session started at 2008-02-25 15:26:53 -0600.]
settings file found
total number of values read 4
1c	3
a4	7
23	c8
1f	98

exercise26 has exited with status 0.

Todd

That could be a problem in the C library. Perhaps you can read the file with fgets(), and then use strtol() to get the hex numbers out?

--
Mats

No, "rt" is perfectly standard. The standard says you can have one of "r", "w", and "a", followed by an optional "+", followed by an optional "t" or "b". (The "+" can also go after the "t" or "b").

The "t" in "rt" means "text file" -- and only DOS/Windows systems (AFAIK) differentiate between binary files and text files (which have line ending conversion). Perhaps that's what you were thinking of.

Stick fopen() into google.

• http://www.cplusplus.com/reference/c...dio/fopen.html
• http://opengroup.org/onlinepubs/0079...xsh/fopen.html
• http://www.cppreference.com/stdio/fopen.html
• http://man.he.net/man3/fopen
• http://www.opengroup.org/onlinepubs/...ons/fopen.html

It's part of the C89 standard. Most of those references say so. (C99, too, if the last link is to be believed.)

I think you'd be hard-pressed to find a reference that says it's not part of the standard . . . which is different, mind, than not mentioning it at all.

It's part of the C89 standard. Most of those references say so. (C99, too, if the last link is to be believed.)

My copy of C99 (the final version, not the draft) does not mention 't' as part of the mode argument. As far as I can tell, all the pages you linked to do not mention 't' as part of the mode argument. Are you sure you are not confusing '+' and 't'?

I always thought it wasn't part of the standard, and was just used to avoid confusion by explicitly stating you've opened it in textmode.