Thread: why this while condition doesnt stop the loop??

i looked at his code
and you open the same file
i changed that and i open 3 different files(that we used earlyer)
and then your code gets a run time error
and when i degubbed it
smallest functions gets 3 NULLs instead of data

??

Code:

#define _CRT_SECURE_NO_WARNINGS

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

struct FileData
{
	FILE *f;
	char *s;
};

void readOneStr(struct FileData *fd)
{
	char temp[100];
	if (fgets(temp, sizeof(temp), fd->f))
	{
		temp[strlen(temp)-1] = 0;
		fd->s = realloc(fd->s, strlen(temp)+1);
		strcpy(fd->s, temp);
	}
	else
	{
		free(fd->s);
		fd->s = NULL;
	}
}

char *findSmallest(char *s1, char *s2, char *s3)
{
	char *smallest = s1;
	if (!smallest || (s2 && (strcmp(s2, smallest) < 0)))
	{
		smallest = s2;
	}
	if (!smallest || (s3 && (strcmp(s3, smallest) < 0)))
	{
		smallest = s3;
	}
	return smallest;
}	


void readStrs(struct FileData *f)
{
	char *smallest = findSmallest(f[0].s, f[1].s, f[2].s);
	int i;
	for(i = 0; i < 3; i++)
	if (!f[i].s || !strcmp(f[i].s, smallest))
		readOneStr(&f[i]);
}

void compareAndOutput(FILE *out, struct FileData *f)
{
	if (f[0].s && f[1].s && !strcmp(f[0].s, f[1].s))
	{
		fprintf(out, "%s\n", f[0].s);
		return;
	}
	if (f[0].s && f[2].s && !strcmp(f[0].s, f[2].s))
	{
		fprintf(out, "%s\n", f[0].s);
		return;
	}
	if (f[1].s && f[2].s && !strcmp(f[1].s, f[2].s))
	{
		fprintf(out, "%s\n", f[1].s);
		return;
	}
}

int main()
{
	struct FileData f[3] = { NULL };
	FILE *out = fopen("g:\\out.txt", "w");

	f[0].f = fopen("g:\\file1.txt", "r");
	f[1].f = fopen("g:\\file2.txt", "r");
	f[2].f = fopen("g:\\file3.txt", "r");

	do
	{
		readStrs(f);
		compareAndOutput(out, f);
	} while(f[0].s && f[1].s && f[2].s);
	return 0;
}

i am using visual studio 2005
"findsmallest is expected to have three NULLs in it. "

your code clearly shows that you are comparing them in order to find the smallest
so if you get all of them to be NULL then
there is no smallest
??

in some point (line57 ) i get this
http://img26.imageshack.us/img26/3346/56201931.gif

i debugged this code
what2(root, "") just puts 1 into the root->value


what2(root, "a") just puts 1 into the root->sons[0]->value
but that doesnt give me a pattern

Code:

#include <stdlib.h>
#include <stdio.h>
#define N 3
typedef struct tree {
   int value;
   struct tree **sons;  // array of pointers 
} tree;

tree * CreateLeaf(){
   int i;
   tree *temp = (tree *)malloc(sizeof(tree));
if(!temp) exit(1);
   temp->value=0;
   temp->sons = (tree **)malloc(N * sizeof(tree *)); 
   if(!temp->sons) exit(1);
   for(i=0; i<N; i++)
  temp->sons[i]=NULL;
   return temp;
}

void what2(tree *root, char *text){
   if(!(*text)){
      root->value++;
      return;
   }
   if(!root->sons[*text-'a'])   
root->sons[*text-'a']= CreateLeaf();
   what2(root->sons[*text-'a'],text+1);
}

void what3(tree *root){
   int i;
   if(!root) return;
   printf("%d ",root->value);
   for(i=0; i<N; i++)
      what3(root->sons[i]);
}

void main(){
tree *root= CreateLeaf();
what2(root, "");
//what2(root, "a");
 

}

another problem is understanding the structure

Code:

temp->sons = (tree **)malloc(N * sizeof(tree *));

temp->sons is now a pointer to a pointer to an node
then they say

Code:

root->sons[*text-'a']= CreateLeaf();

suppose that *text='a'
so

Code:

root->sons[0]= CreateLeaf();

what is sons[0]

sons[0] is row 0 its a whole row of members
its not one node for which we can make it to point to something else

a whole row cannot point to anything
this line

Code:

root->sons[0]= CreateLeaf();

makes no sense
??

this is the formal solution:

i cant understand the red marked part

what is the purpose

Code:

typedef struct vote {
	char name [30];
	int id,type,candidate;
} vote;
void report(FILE* college[3], FILE* arr[10], char* canceled){
// Fuction returns the minimal id
int getMin(int eof[],vote [],int *);
// Function checks a vote record correct
int votecheck(vote ,vote [],int i);
// Function reads the next record from "college" file
int readFrom(FILE *,vote [],int);

void  report(FILE *college[3], FILE *arr[10], char*canceled){
	FILE *cancel;
	vote currtable[3], // array for three current "college" records
		votable[3],    // array for checking the records with the same "id"
		current;	   // struct for the current "college" record	
	int i,j,idmin,index,flag,eof[3];
	if(!(cancel=fopen(canceled,"w"))) exit(1);
	
	for(i=0;i<3;i++)
		eof[i]= readFrom(college[i],currtable,i);
// main loop	
	while(eof[0]!=EOF||eof[1]!=EOF||eof[2]!=EOF){
		idmin=getMin(eof,currtable,&index);
		for(i=flag=0;i<3;i++)
			if(i!=index && eof[i]!=EOF && currtable[i].id==idmin)
				flag=3;
		if(flag){
		fprintf(cancel,"%s%d%d\n",currtable[index].name,idmin,flag);
			for(i=0;i<3;i++)
				while(eof[i]!=EOF && currtable[i].id==idmin)
				eof[i]=readFrom(college[i],currtable,i);
			continue;
		}
//Filling struct table for the minimal id
		votable[0]=currtable[index];
		i=1;
		while(eof[index]!=EOF && i<3){						eof[index]=fscanf(college[index],"%30[^\n]%9d%1d%1d%*c",
current.name,&current.id,&current.type,&current.candidate);
		if(current.id!=idmin){
			for(j=0;j<i;j++)									fprintf(arr[votable[j].candidate],"%9d%d%d\n",
idmin,index,votable[j].type);
		currtable[index]=current;
		break;
		}
		else{
			flag=votecheck(current,votable,i);
			if(flag){				fprintf(cancel,"%s%d%d\n",currtable[index].name,idmin,flag);
			while(eof[index]!=EOF && currtable[index].id==idmin)
			eof[index]=readFrom(college[index],currtable,index);
			break;
			}
			else
				votable[i++]=current;
		}//else
	}//while
	if(i<3)  continue;
		if(eof[index]!=EOF)
		eof[index]=fscanf(college[index],"%30[^\n]%9d%1d%1d%*c",
current.name,&current.id,&current.type,&current.candidate);
		if(eof[index]==EOF ||current.id!=idmin ){
			for(j=0;j<i;j++)
				fprintf(arr[votable[j].candidate],"%9d%d%d\n",
idmin,index,votable[j].type);		
			currtable[index]=current;
		}
		else{			fprintf(cancel,"%s%d%d\n",votable[0].name,idmin,2);
	while(eof[index]!=EOF && currtable[index].id==idmin)				eof[index]=readFrom(college[index],currtable,index);
		}
	}// main loop - while
	fclose(cancel);
}// report

int votecheck(vote curr,vote arr[],int i){
	int j,count;
	for(j=count=0;j<i;j++){
		if(curr.candidate==arr[j].candidate)
			return 1;
		if(curr.type==1 && arr[j].type==1)
			return 2;
		if(curr.type==2 && arr[j].type==2)
			count++;
		if(count>1)	return 2;
	}
	return 0;
}

int readFrom(FILE *coll,vote table[],int i){
	return fscanf(coll,"%30[^\n]%9d%1d%1d%*c",table[i].name,
				&table[i].id,&table[i].type,&table[i].candidate);
}	

int getMin(int eof[],vote table[],int *index){
	int i,idmin;
	for(i=0,idmin=999999999;i<3;i++)
		if(eof[i]!=EOF && table[i].id<idmin){
				idmin=table[i].id;
				*index=i;
		}
	return idmin;			
}

there are places which i dont know what is the purpose in that part,
i will try to explain myself every part:

Code:

	for(i=0;i<3;i++)
		eof[i]= readFrom(college[i],currtable,i);

it reads one line from each college file and puts it into currtable.

Code:

	while(eof[0]!=EOF||eof[1]!=EOF||eof[2]!=EOF){
		idmin=getMin(eof,currtable,&index);
		for(i=flag=0;i<3;i++)
			if(i!=index && eof[i]!=EOF && currtable[i].id==idmin)
				flag=3;
		if(flag){
		fprintf(cancel,"%s%d%d\n",currtable[index].name,idmin,flag);
			for(i=0;i<3;i++)
				while(eof[i]!=EOF && currtable[i].id==idmin)
				eof[i]=readFrom(college[i],currtable,i);
			continue;
		}

idmin is a minimal id.
index represents the file from which the minimal id came from.
if there the same id from there is another then flag=3
and it puts the whole minimal row to cancel file.
then i am not sure but they take the next line of idmin

but index is holding the number of file from which idmin came from
i cant understand this last while??

and why they use continue;
??