K&R variable confusion

**deadhippo** · 05-22-2008

This is a question for those familiar with K&R and for those who don't need to be. On page 29 second edition you can find the following function as part of a program. I don't understand how the value of "lim" is decided.

Code:

int getline(char s[], int lim)
{
	int c, i;

	for (i = 0; i < lim - 1 && (c=getchar()) != EOF && c != '\n'; ++i)
		s[i] = c;
	if ( c == '\n')
	{
		s[i] = c;
		i++
	}
	s[i] = c;
	return i;
}

I believe this function will return the length of the program but I can't figure out how if it doesn't know what lim is.

**stevesmithx** · 05-22-2008

MAXLINE is the second argument of the function getline.
It is a symbolic constant defined as 1000.
So 'lim' would have 1000.

**swoopy** · 05-22-2008

lim is the size of the s[] array. It's how many char can fit into s, minus the string terminator, which takes up one element. The function is similar to the library function fgets().

**deadhippo** · 05-22-2008

Thanks for your replies.

@stevesmithx - The program does define MAXLINE as 1000

Code:

#define MAXLINE 1000

but the function getline uses lowercase so I guess it is not the same

Code:

int getline(char line[], int maxline);

Of course I could be wrong.

@swoopy - How does the program determine the value of lim? I see it is declared as an int but that is all.

**stevesmithx** · 05-23-2008

Sorry,I misinterpreted your Post.

but the function getline uses lowercase so I guess it is not the same
Code:
int getline(char line[], int maxline);

It's just a function prototype.
It doesn't really matter.
Any variable name is given in a prototype.
It can even be ignored like this:

Code:

int getline(char * , int );

As swoopy said,lim is the size of the array.

It is used for safety reasons in case the line is more than 1000 chars long.

**deadhippo** · 05-23-2008

Originally Posted by stevesmithx

It is used for safety reasons in case the line is more than 1000 chars long.

Are you saying that the value of lim is 1000? And of so where is the connection in the program from the number 1000 to the variable lim?

**stevesmithx** · 05-23-2008

Are you saying that the value of lim is 1000? And of so where is the connection in the program from the number 1000 to the variable lim?

Yes.
See the calling function and called function.

Code:

len = getline(line, MAXLINE)

and

Code:

int getline(char s[],int lim){
...
}

Clear explanation is given in the K&R book.

**deadhippo** · 05-23-2008

Yes, I see it now. Thanks a lot.

Unfortunately I don't feel the explanations are that clear but hopefully it will get clearer as time goes on. Thanks for your patience.

**Elysia** · 05-23-2008

Originally Posted by stevesmithx

It can even be ignored like this:

Code:

int getline(char * , int );

Might I add that that's considered bad practice? Don't remove the argument names from the prototypes.

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