Thread: Lvalue error? Whats that?

Hello there again. My programm runs swimmingly up until my bubble sort. The error I am getting is "Lvlalue required in function main" and I'm not to sure what that means. It is right at the bottom. I am also not to sure if I have the number of times it sorts correct. (It needs to loop N times, where N is the number of words the user wants to enter)

(commenting out the bubble sort makes the program compilable, if you need to see what it should do).

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

char **p;
char size[20];
char buff[21];
char temp[21];
int N;
int j,i,k,l,m,d,s,a,b;

int main()
{
	do{
		d=0;
		printf("How many words would you like: ");
		fflush(stdout);
		for(j=0; j<20; j++)
		 {
		      size[j]=fgetc(stdin);
		      if (size[j]=='\n')
		      {
		        size[j]='\0';
		        break;
		      }
		 }/* end j-loop */
			if (j==0){
				printf("That input is empty.\n");
				d=1;

			}
		    if (j==20) {
		      printf("That input is too long.\n");
		      while(fgetc(stdin)!='\n');
		      d=1;
		  }
}while(d!=0);


	printf("You want %d words.\n", atoi(size));

	N=atoi(size);
	p=(char**)malloc(N*sizeof(char*));
		if (p==NULL)
		{
			printf("Memory error");
			exit(0);
		}
	for (i=0; i<N; i++)
		p[i]=(char*)malloc(21*sizeof(char));
		if (p[i]==NULL)
		{
			printf("Memory error");
			exit(0);
		}
	printf("Do not enter more than 20 characters.\n");

	for(k=0; k<N; k++)
	{
		A:printf("Enter a word: ");
		fflush(stdout);
		for(m=0; m<21; m++)
		{
		      buff[m]=fgetc(stdin);
		      if (buff[m]=='\n')
		      {
		        buff[m]='\0';
		        break;
		      }
		 }

		    if (m>=21)
		    {
		    	printf("Word is more than 20 characters.\n");
		      	while(fgetc(stdin)!='\n');
      			goto A;
			}
			if (m==0)
			{
				printf("That input is empty\n");
				goto A;
			}
		strcpy(p[k],buff);
	}
	printf("\n");
	printf("Your unsorted list of Names:\n");
	k=0;
	for(k=0; k<N; k++)
		printf("%s\n",p[k]);


	for (a=N; a>0; a--)
	{
		for (b=0; b<a; b++)
		{
			if(strcmp(p[b],p[b+1])>0)
			{
				temp=p[b];
				p[b]=p[b+1];
				p[b+1]=temp;
			}
		}

	}
	printf("\n");
	printf("Your sorted list of Names:\n");
	k=0;
	for(k=0; k<N; k++)
		printf("%s\n",p[k]);



return 0;
}

Originally Posted by Elysia

Glad you asked.
You can try to make it look more like the example @ http://cpwiki.sf.net/Indentation
Or try reading the in-depth guide at http://cpwiki.sf.net/User:Elysia/Indentation

awesome, im taking a look at these now, thanks so much for your help. Also, for some reason in my program the value "2" for N doesn't work, but every other number does...I get a memory allocation error

Is it really that bad to mix? If it is a really big block with ifs, whiles and fors inside, then I use

Code:

if(whatever)
{
   bla bla...
}

and if it is a small block with nothing nesting inside I use

Code:

if(){
    ....
}

So my code almost always looks like this:

Code:

while(whatever)
{
    if(something)
    {
         blaablaalbaa;
         blaaa blaaa;

         if(something){
             code code;
             code code;
         }

         etc. etc.;
    }
}

what do you think? Tell me if its bad because I'm also trying to get rid of my other bad habits:

Code:

thing1,thing2,thing3 instead of thing1, thing2, thing3
a=b+2 instead of a = b + 2 (or better) a = b+2
if((ch=fgetc(file))!=EOF) instead of if( (ch = fgetch(file)) != EOF)

Originally Posted by Elysia

Huh? Your "bad habits" should be the other way around. The more readable, the better.

I mean... my bad habit is the first one... and I should change it for the second one.
I never separate commas

Code:

thing1,thing2,thing3

I never separate assignments

Code:

this=that*(2+(something/5))

etc. etc. All the code I've seen always separates that kind of stuff.

Originally Posted by vart

It is bad... when you just scan code for possible errors - you do not count how many lines are in the block... you look for pairs of brackets - if opening one is missing - you need to stop scanning and start looking for it. So you need to be consistent in your style...

hmmmmm..... I think I'd be better off with

Code:

if()
{
}

because when the blocks get way big it is a lot easier. But I use Notepad++ which always throws a neat line between indents, so

Code:

if(){
}

is easy to find too. But well, for other editors and plain text I think the first one is a better choice.