Questions tagged [hash-table]
The hash-table tag has no usage guidance.
85
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pset4 speller - can't pass valgrind test - 32 bytes still reachable
Can't pass valgrind test on pset4 speller (hashtable). The speller works perfectly but, I'm getting this message from valgrind:
==3911==
==3911== HEAP SUMMARY:
==3911== in use at exit: 32 bytes ...
- 101
6
votes
1
answer
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How to fix the "conditional jump or move depends on uninitialized value" valgrind error?
Need help again.
I've got my linked list working. It copies a list of words from a file into a linked list.
Now I want to make a hash table so that all words starting with the letter 'A' go into a ...
- 65
2
votes
1
answer
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CS50 good hash function for PSET5 Speller
I was looking up different hash functions and was getting really confused following what the code was doing. I stumbled upon this hash function:
int hash(const char * str) {
int hash = 401;
...
- 79
2
votes
1
answer
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How to know how many buckets for hash table - Speller PSET5
I am implementing the hash table for load at the moment, but I don't know how I should figure out how many buckets I should be using. Is there a 'rule' for this when creating hash functions, or is it ...
- 144
2
votes
2
answers
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implementation of hash table
I have been having trouble with the implementation of the hash table and linked lists. I don't know if I am on the right track or not, but I think my main problem is not knowing how to automate the ...
- 149
2
votes
2
answers
131
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how effective would it have been to use an array for the dictionary?
I just completed pset5 using a trie, but I'm curious about other methods.
How effective would it have been to load the dictionary into an array and then use a binary search function to locate words ...
1
vote
2
answers
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how to check if just the load function is implemented correctly?
I've just started this pset and only implemented load.
So how do I know if my load function actually loads the dictionary and there are words in the hashtable without implementing the other functions ...
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1
vote
1
answer
676
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pset5, load function. Initializing elements in hashtable to null
This is my load function from dictionary.c.
I'm trying to create a hashtable of linked lists with separate chaining. There are 26 elements corresponding to each letter in the alphabet. My questions ...
- 215
1
vote
2
answers
379
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Why should we mod a hash value by the size of the hash table?
Week 7 Short on Hash Table provides the following suggested hash function:
int hash_function (char* key)
{
// hash on first letter of string
int hash = toupper(key[0]) - 'A' ;
return hash ...
1
vote
1
answer
163
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Pset5: Hashtable, cannot submit my code
I am unable to submit my code to test it against other cs50 students
:) dictionary.c and dictionary.h exist
:) speller compiles
:( qualifies for Big Board
expected exit code 0, not 139
How ...
user23063
1
vote
1
answer
638
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pset5 speller.c with hashtable errors and seg fault
this is my code so far for pset5. I would appreciate giving me hints about my erros. I also get a segmentation fault. thanks.
when I implemented load and check only, it seemed to load the text and ...
- 121
1
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1
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954
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Pset6: Is it possible implement a 3D Hash table Matrix?
It might be too early on for me to ask questions in this problem set, as I am just getting started with load. I was looking up Hash Functions, and they look a little cryptic to me. Is it possible to ...
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1
vote
1
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500
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malloc an array - hash table - Pset 6
Initially i had no problems implementing my hash table during the load function.
however when it came time to check for errors, i couldn't access my hash table in order to traverse my linked list.
I ...
- 11
1
vote
1
answer
425
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My check function in speller isn't working
I have implemented everything else but this check function when I try to test it it seems like the the check function isn't working, because the no. of misspelled words is the same as the no. in text.....
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1
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0
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Is hash table a type of dictionary?
In week 7 shorts for trie it is said that "a dictionary is a type of data structure that maps a key (usually string) to value".
So is hash table considered a dictionary too?
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1
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2
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PSET5 Speller hash function
I have been working on the speller problem in pset5 for a while now, and I am not able to figure out the problem in my hash function:
unsigned int hash(const char* word)
{
int M = 1000000001;
...
- 146
0
votes
1
answer
110
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PSET6: Sorted List?
I just finished pset6 following the videos of Zamyla and the section. At the end I realized that my code implements a sorted linked list (via strcmp) but then I don't take advantage of that in my ...
0
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1
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470
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When declaring an array of pointers that will be a hash table, do you have to set all the elements of the array to NULL?
In the distribution code for Speller in pset5, they include this line in dictionary.c
// Hash table
node *table[N];
Should I set every element in the array to NULL, because they are pointers? (the ...
- 3
0
votes
1
answer
325
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PSET 4 - Speller: Every single word is misspelled
When I run the program, all words are considered misspelled. I can't figure out where the problem is. Can someone please help me?
It also says that my program is free of memory errors - can't check ...
- 3
0
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1
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394
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Speller 2019: dictionary could not be unloaded and the program identifies misspelled words wrongly
my code does not work so well because it could not unload the dictionary/large eventhough there are no leaks in memory. My programm does also identify the misspelled words wrongly.
Just comment if ...
0
votes
2
answers
184
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Speller (Hash) not handling substrings properly
All tests seem to pass okay apart from the substrings test.The results of this test are :
:( handles substrings properly expected "MISSPELLED WOR...", not
"MISSPELLED WOR..." Log running ./...
- 29
0
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2
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557
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PSET4 Speller(hashtable) cs50 2019 HELP!
Can somebody please help me whenever i execute check50 on my code i get this
:( handles most basic words properly
expected "MISSPELLED WORD...", not "MISSPELLED WORD..."
:( handles min length (1-...
0
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1
answer
410
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How can I optimize load in pset5
I'm trying to optimize my load function (after using gprof to profile speller), as it takes 99.6% time of my program. How can I do it?
Here is dictionary.c:
/* This function opens a dictionary file ...
- 3
0
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2
answers
340
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Pset5 - Problem with hash table load(), malloc, and segmentation-fault
I am having problem with the load function. When I run:
valgrind --leak-check=full ./speller texts/austinpowers.txt
it gives me the following report (I am using the small dictionary to test my code) ...
- 17
0
votes
3
answers
313
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Declaring struct node and node array globally (hashtable implementation)
When coding load (using the hashtable method), I declared the structure for a node and an array of nodes within the function. However, this--of course--means I can't use these things in the check ...
- 31
0
votes
2
answers
138
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Hash tables running time
In the week 6, it was said for hash tables that - "We could even combine names and birthdays somehow to create a larger hash table that’s even more uniform and have smaller chains, and be even faster"
...
- 161
0
votes
1
answer
247
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Speller not working! What's going on?
My function returns this:
WORDS MISSPELLED: 375902
WORDS IN DICTIONARY: 143091
WORDS IN TEXT: 376904
TIME IN load: 0.02
TIME IN check: 1.20
TIME IN size: 0.00
TIME ...
0
votes
1
answer
46
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Speller skips last word in testfile I use
The title speaks for itself, but here is a bit more in-depth explanation. While my check() function runs, it always skips the last word in whatever file it is checking out. The source code for my ...
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0
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1
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65
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CS50 (Speller) returns all words as misspelled
I'm right on the verge of cracking this problem. I ran the program on the small dictionary provided in the distribution code. It returned both words as misspelled. So I debugged the program. I noticed ...
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0
votes
1
answer
151
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PSET5 Compiling issue
So I finally finished my code and received 20 errors when attempting to compile, after my first attempt fixing the errors I tried again and received 15 errors, once more and received 17, and now am ...
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0
votes
1
answer
60
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Speller.c doesn't work
I've spent pretty much time trying to solve a speller and got really stuck, don't know what's wrong with my code. It compiles but check50 says it's totally incorrect. I would be grateful if you could ...
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0
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1
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on pset4 speller load() struggling to understand if populating dictionary correctly and how to check hashtable
I am building my load() function and I'm wondering if I'm building it so that it is indeed storing the dictionary words correctly.
I tried printing both:
printf("%s\n", new_node->word); //to see ...
- 125
0
votes
1
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75
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speller double free or corruption hashtable
I'm getting a "double free or corruption" error when running this code. I don't know in which function the error is. I get the error after the code has run through check, before it gets to the unload ...
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0
votes
1
answer
51
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do not understand why check function checks new word against dictionary
I am trying to implement the check function of Speller in CS50. The code below may or may not work. But the thing that gets me is that I don't understand the bit :
if strcasecmp(cursor-> word, ...
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1
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I keep getting the message that 'non-ASCII characters are not allowed outside of literals and identifiers.'
I keep getting the message that 'non-ASCII characters are not allowed outside of literals and identifiers.' I get this message when I compile and it is at the strcpy section. Any help gratefully ...
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1
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160
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CS50 [Speller_hashtable] my hashtable is weird!
After debugging for a long long time, it turned out that my hashtable must have some problem. Therefore, to find out where the problem is, I put this line of code after I insert a word in the ...
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0
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1
answer
149
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PSET4 (Speller) malloc and calloc usage
After getting my code to work, i looked if there were any memory leaks using valgrind. It found no memory leaks, however it returned these two errors:
==7109== Conditional jump or move depends on ...
- 103
0
votes
1
answer
524
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Speller (hash) memory leak?
The program seems fine to me (other than this, it runs as intended), when I run valgrind, it says:
==5101== Memcheck, a memory error detector
==5101== Copyright (C) 2002-2017, and GNU GPL'd, by ...
- 109
0
votes
1
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69
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I can't figure out what's wrong with my speller (hash) code
When I try to run it, it says that there are no words in the dictionary so there's probably something wrong with the load function.
My load code:
// Loads dictionary into memory, returning true if ...
- 109
0
votes
1
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94
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Speller(hashtable) VALGRIND ERRORS!
i don't know or understand through val grind where and what i'm doing wrong. Except for memory errors my code outputs as correct in check50.
my code
// Implements a dictionary's functionality
#...
0
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1
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471
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PSET5 "Linker Command Failed with Exit Code 1"
I've been working on speller (implementing a hashtable) for quite a while now and I'm stuck...my code compiles but I'm assuming there's a run-time error. I'm not sure what to make of my error message, ...
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2
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pset4 speller all words are misspelled
I realize that many people have asked this question before but I didn't find my answer in any of them. Or maybe I'm just too stupid to see it.
Anyways my code seems to work except that all the words ...
- 1
0
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1
answer
140
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CS50 - Speller (Hashtable) - Misspelled all words
My program is misspelling all words in the texts. There is a problem somewhere in either load or check, but I just can't figure it out. Can you guys help me find the problems I am having in my program?...
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0
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2
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1k
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pset4 Speller hash table basics
After struggling with this pset for a while I decided to strip it down to its most basic form and try and understand the implementation of hash tables and linked lists by creating my own. To that end ...
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0
votes
1
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140
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pset5 load null pointer issue
Working through the load portion of pset5. Everything compiles, but when I run valgrind it looks as if nothing is actually loading in, with the error of "null pointer passed as argument 1, which is ...
- 37
0
votes
1
answer
135
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HashTable full of single value
I think the problem is in my load function. I am able to successfully create a hash for each word, and I can call my createNode and insertNode functions to such a degree that I create a full hashtable ...
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0
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1
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123
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Two hash table questions
I am working through SPELLER and have a few questions. When I create a new node node *newptr = malloc(sizeof(node)); do I need to say newptr1, newptr2, newptr3 and if so what is the best way of doing ...
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1
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722
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Struggling with hash table! Pset5
I've been trying to fix this bug for the past couple of days, but it seems this one I really can't figure out on my own. Hope you guys can help a bit.
Here's the code for my load function in pset5.
#...
0
votes
1
answer
520
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Segmentation Fault on Hashtable
PLease Someone help me
I was trying to implement a hash table that stores the word of English language for pset 5. So to be in brief, I used an array of linked list ( Chaining ) , I haven't made the ...
0
votes
1
answer
320
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Speller(hashtable) flagging all words as misspelled
I've exhausted all my options which is why I'm making this post. When I simply run the program it prints every word as misspelled. The problem itself probably lies in load or check. Running the ...
