Questions tagged [hash-table]
The hash-table tag has no usage guidance.
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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 ...
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Segmentation fault occurs if I delete an unused global variable in Pset5
It looks I have broken C while working on Pset5, I mean, I don't understand a bit why this happens.
First, I completed the problem with the simplest of hash functions which just processes the first ...
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Too many misspelled words - speller.c PSET-5
I'm using a hash table to implement the spell checker for speller.c with a hash function I found on reddit but it prints out way too many misspelled words and I have no idea why. Any help would be ...
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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
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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 ...
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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
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Pset5: I get a seg fault when looking for a word that is not in the dictionary
I get a seg fault when running the code below. I ran GDB and what I can tell is that it works well when the word I look for is in the dictionary (e.g. this), but that it does not work when the word is ...
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Pset5 segmentation fault in load function using hash table
I always get a seg fault in this specific function. I've checked it with GDB, and the line causing seg fault is hashtable[index]->next = tmp_node.
bool load(const char* dictionary)
{
FILE* dict = ...
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Pset5 - dictionaries.c : My check output is very unrelated and confusing
i believe my load function is already working properly, i use fgets, and i have deleted the newline character in each word.
but when it comes to check (i think..) it gives me unrelated output. this ...
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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 ...
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Unload-function seems to trigger segfault
I'm having some difficulties with pset5 - Mispellings. My program, which uses a hash-table, seemed to work fine until I implemented the unload-function. I used the function shown in the walkthrough by ...
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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 ...
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My hash table works and has good running time but fails one check - :( handles max length (45-char) words
My hash table works and has good running time but fails for one check (rest all checks pass) - :( handles max length (45-char) words
AFAIK pneumonoultramicroscopicsilicovolcanoconiosis is the longest ...
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pset5 Load: Am I on the right track? Getting errors for pointer/integer confusion
As the title suggests I having a bit of trouble with my if and else down at the bottom of my code. Errors are arising that say incompatible pointer to integer conversion. I am a bit confused as to ...
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pset5 speller: loads one more word
Whenever I load words from the dictionary and check the number of words in the dictionary, it seems to load one more than there actually is. For example, if I load the SMALL dictionary, number of ...
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What's wrong with my load function? for cs50, pset5. Im sure all other functions are correct
I tried to figure it out using gdb, failed miserably.
bool load(const char* dictionary){
FILE* fp = fopen(DICTIONARY, "r" );
new_node = malloc(sizeof(struct node));
while(!feof(fp))
{
...
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PSET5 What LOAD really supposed to do?
I'm starting Problem Set nb 5 and just need a couple more specifications to begin my implementation of LOAD.
Is it good to assume that a lexicographically sorted dictionary corresponds to a ...
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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 ...
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CS50 dictionary.c problem with hashtable
Im having troubles with the hashtable in pset5, in the part where you check wether a word is in the dictionary.
My code looks as follows:
bool check(const char* word)
{
int n = strlen(word);
...
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error: expected expression. Compling problems!
Right where it says " <= 'Z' " the complier puts a ^ to the < sign and says error: expected expression. I included . I have no idea what is wrong with this statement!
int hash_func (char* key)
{...
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Segmentation error with array of nodes
I don't understand why I am getting segmentation error. Is it because I'm setting the array to NULL? Though if I don't set it to NULL then the head of the list will always keep the value of zero.
...
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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"
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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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How do I pass back the location of my loaded dictionary?
I have (hopefully) loaded the dictionary correctly, but I'm not clear on
how to identify its location in memory without changing the declaration of the load function?
More concretely, in my code for ...
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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 ...
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Am I creating an array of pointers or an array of structs?
I've read an answer to a similar question about
node* new_node = malloc(sizeof(node));
and how it allocates memory for the pointer plus all the data contained within the struct as it was declared
...
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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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How are associative arrays like hash-tables?
In week 9 lecture, David said:
An associative array is one in which you can store key value pairs where
the key is not necessarily a number. It could in fact be a string, a word.
And so this ...
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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 ...
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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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pset6 load seg faulting when accessing malloc'd node
I need some guidance on where I'm going wrong here.
GDB runs fine until I try to access the "next" property of a node to see if it's NULL.
Am I just confusing how the node structure works? My ...
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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 ...
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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 ...
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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 ...
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What is wrong in this implementation of hash table?
The following implementation for insert() function that inserts input into a hash table namely first each of which elements are pointers to a linked list works well.
// takes the number to be ...
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