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Hello,
I am making a c program, and i was wondering if anyone knew of a way of counting the number of lines in a text file. I have files with numbers in it, but i dont know how many lines there will be, e.g
23, 23.4, 2.445
756, 5467, 56
...
...
However, I know that each line is termnminated using \n so by counting the number of times that '\n' is written i could find out the total number of rows.
Any ideas?
Thanks.
That is one way; another would be if you are reading the file in line by line (eg with fgets) you could count lines that way.Quote:
Originally Posted by rmc
Thanks for the reply.
Unfortunately im very new to programming, how could you use fgets exactly.
All im doing is storing the data in an array, but i dont know how big to make the array unless i know the number of rows.
???
You use fgets like it says how to in the manual.
i am very sorry for that............my apologies...........i am new to the forum and i dont know how to start a new thread...........please help me in doing so..............i will be very thankful
You can search the Web, e.g., you might find cppreference.com's entry on fgets.Quote:
Originally Posted by rmc
Unfortunately, storing an arbitrary number of lines (using just the C standard library) is probably too advanced for you at the moment. Likewise, storing an arbitrarily long line (using just the C standard library) is also probably to advanced for you at the moment.Quote:
Originally Posted by rmc
If you just use fgets(), you have to assume that the lines have some maximum length. One way to avoid this need for an unknown amount of space is to read character by character, and increment your count whenever you encounter a newline.
tabstop is not trying to be dictatorial (we hope); you should consult some documentation first and then if you have problems using a command, etc. ask for help.Quote:
Originally Posted by csvraju
So, in your current circumstance: how are you reading the file who's lines you'd like to count? (ps. before you post code read this)
Well i originally tried it this way, but it doesn't work.
Any ideas why?Code:while (fscanf(myf,"%*[^\n]\n",&line)!=EOF)
{
sum += line;
}
That depends on what you mean by "sum", "line", and "doesn't work".
Well, i thought that the sum would be incremented by 1 after each \n, however the sum is not equal to the total number of lines.
It's easier to pinpoint a problem in this procedure if you use fgets() to get a line from the file and sscanf() on the line to extract your data. So for example:
The outer layer of brackets is a truth test the same as this:Code:char line[64]; /* should be long enough for this, right? */
float data;
FILE *fh; /* obviously this should be fopend, etc. */
while ((fgets(line,8,8,fh))) {
sscanf(line, "%f", &data);
}
Since fgets returns NULL at end-of-file.Code:while (fgets(line,8,8,fh)!=NULL) {
Once you have everything worked out you can always change it back to the straight fscanf().
For counting the lines add this to the loop:
Code:sum++;
Why should line be 1? Why wouldn't it be whatever number you read in from the file?Quote:
Originally Posted by rmc
Also, it would get added to after every number, not every line.
So, in your current circumstance: how are you reading the file who's lines you'd like to count? (ps. before you post code read this)[/QUOTE]
Code:FILE *fp;
fp = fopen("U:\\data.txt", "rt");
Okay, that's how you open the file. How are you reading the file?Quote:
Originally Posted by rmc
The OP has admitted to fscanf().Quote:
Originally Posted by tabstop
Quote:
Originally Posted by MK27
Yes, the maxiumum length of a file will be 60 rows.
However, my program will not compile at this section
there are too many arguments to function fgets.Code:while (fgets(line,8,8,fh)!=NULL) {
Also using
I am sure that it recognises the correct number of lines in the file, but it does not store it in 'number' correctly, nor does it increment the sum either.Code:while (fscanf(fp,"%*[^\n]\n",& number)!=EOF)
sum++;
I think you've gotten turned around on what fscanf does. For one thing, the * suppresses assignment, so by definition nothing will get stored in number. (This is probably a good thing, since it will try to store a bunch of characters in that address, as opposed to a float, which I think is what number was.) Secondly sum is indeed getting incremented unless your file is empty. (No really, I just tried it here on this machine.)
Whoops! Sorry sorry sorry... I was thinking about fread(), which takes a number of chunks and a size for each chunk. fgets() just takes a size, so that should be 64 (it only reads up to 63 tho, because it leaves room for a null terminator).Quote:
Originally Posted by rmc
fscanf() returns the number of successful "assignments" (ie, the number of variables written into), so you could try a check on that:
This will tell you whether "&number" got written into. If the answer is 0, your template does not work with your material. That's why I'm recommending fgets with sscanf, because it is FAR EASIER to make fgets work than fscanf, and you won't have to mess around with \n in the template (which I could be wrong, but I don't think that works anyway).Code:int x;
x=fscanf(.....
printf("fscanf returned %d\n",x);