Thread: Read a well defined number of lines only

Maybe something like this?

Code:

while((fgets(line), sizeof(line), file_id)!= NULL) { //
  if(line[0] =='\n')
    break;
  //continue with the rest of your processing
}

You could also test it using ctype.h header with any of several functions to confirm that line[0] is a number, is an alphanumeric, is not a space, etc.

or

Code:

if(line[0] < '0')  //zero, not Oh
  break;

The above would catch lines with blank spaces (which are 32 ascii), and newlines (ascii 10), but catch all numbers and letters, since 0 is 48 ascii.

I believe I like the < '0' one better since it would be the more robust one to use.

How about that?

Hi Adak and Quasah,

Thank you very much to both. I actually tried all the options, and although both options suggested by work fine, I could not get Quasah's to work.
What happens with Quasah's solution is what would happen without using such solution and keeping the function as the original version.

I really appreciate your help

Thank you
Best

Hello Adak,

Look, I have a similar issue to this posted earlier today and to which you helped me find a solution; now, instead of being able to recognize the additional blank lines at the end of the file, I want to be able to count correctly the number of entries within each row, independently on the size and type of "separator" between the entries.
The code that I put below fails when, instead of 1 space between two consecutive numbers on the same line, there are 2 or more spaces, or when the line begins with a space instead of a number.
I tried to see how I could apply your algorithm of above to this problem but I couldn't figure it out.

I hope you can help with this as well,
I appreciate.

Ex. File 1: this is read correctly

Code:

1 2 3
4 5 6
6 7 8

Ex. File 2: this is not read correctly:

Code:

 1  2  3
 4  5  6
 5 6  7
   8  9 10

Code:

while(fgets(line, sizeof(line), mesh_file_id)!= NULL) {
			line_cntr++;
		
			if(line_cntr > 0 && line_cntr <= nrows ){
				ptr_conn = strtok(line, SEPARATOR);

				cntr = 0;
				while(ptr_conn != NULL){
					ptr_conn = strtok(NULL, SEPARATOR);
					cntr = cntr + 1;
					*max_elnodes = cntr;
				}

				i++;
			}
		}
	}//end of: if else

Originally Posted by Adak

Maybe something like this?

Code:

while((fgets(line), sizeof(line), file_id)!= NULL) { //
  if(line[0] =='\n')
    break;
  //continue with the rest of your processing
}

You could also test it using ctype.h header with any of several functions to confirm that line[0] is a number, is an alphanumeric, is not a space, etc.

or

Code:

if(line[0] < '0')  //zero, not Oh
  break;

The above would catch lines with blank spaces (which are 32 ascii), and newlines (ascii 10), but catch all numbers and letters, since 0 is 48 ascii.

I believe I like the < '0' one better since it would be the more robust one to use.

How about that?

Originally Posted by quzah

fgets + sscanf, check the return value of sscanf.


Quzah.

But can I count the number of entries by using sscanf? I dont actually have to store them to any array, but only count them for a subsequent call to another function

thank you again

Thank you!

Originally Posted by quzah

Your welcome. Next time, when I tell you something, try doing a tiny bit of research. You know, like looking up what a function actually does. If you had done that, you'd have known what I was talking about when I told you to check the return value.


Quzah.

Hi Quzah,

Sorry about that, you are right. Thanks fro helping.

All the best,
cfd