Thread: help with fgets and assigning line to variable

hello,

i am trying to paste into a variable the first line i get from a file with fgets. this is done in a loop so if the condition is true it continues and loads the next line from the file into the variable.

Code:

char line[80];
char *mynames;
long counter = -1L;
FILE *names;
 
if ((names = fopen (filename, "r")) == NULL)
{
	perror ("fopen");
	exit (1);
}
else
{
	for counter = 0L;
		fgets(line, sizeof(line), names) != NULL;
		//line = myname;
		counter += strlen(line));

I cant understand how i can place the respective line in the variable mynames. could someone explain me please what i am doing wrong. thanks for your help as i am pretty new with c and i could easilly brake my keyboard right now

Do you really want all lines in memory at the same time, or can you make do with having only one line at a time?

Working with one line is easier and quicker, and is the way I'd recommend for whereever possible.
Loading all lines is tricky and requires you to either pre-allocate space of a fixed size, thus restricting how many lines can be read, OR, use dynamic memory allocation to allow you to hold an (almost) infinite number of lines. The latter requires more advanced coding practices.

Decide what you want and let us know.

Originally Posted by Intelicopter

hey there... i'm pretty new to c too, but i've had to do a similar thing when i was sending configuration strings to a gps... but anyway, check this out... works for me.

There are a few problems with your code. I'll point them out for you:

Code:

void main(void)

Main is not a void function, ever. The FAQ will give you an explanation of the reason this is wrong. Main always returns an integer.

Code:

 cfgfile = fopen("strings.txt", "r");

 if (cfgfile==NULL) printf("can't open file\n");

If the file fails to open, you display a message saying it can't open it. Then, you continue on anyway. You should be exiting the program right here, or resolving it some other way. Instead, you just print a message and keep on going, trying to use the file anyway...

Code:

cfgstring[i][strlen(cfgstring[i])-1] = '\0';      // remove CR from line

It's possible here that your line you just read doesn't contain a newline. As such, you'll just end up writing over top of some piece of data. A better way would be perhaps something like this:

Code:

char *ptr;

ptr = strchr( cfgstring[i], '\n' );
if( ptr != NULL )
{
    *ptr = '\0';
}

Quzah.