Question

The program basically searches for strings in a given wordlist that are anagrams of the word that is input from the terminal.
It follows the algorithm:

1. Sort all the words in the list
2. Calculate hash values of the sorted words so that all anagrams have the same hash value
3. Create the hash table and start chaining by storing the hash value, the sorted word and the actual word
4. Find the anagrams by checking the hash table

Now the problems is that it runs perfectly on my machine but not on others’ computers. I am including the code here and providing a link for the wordlist. I know it is too much to ask you guys to download the word list and then compile and check but it will mean a lot if you let me know. I am running Ubuntu 11.04 with 2.6.38-13-generic-pae

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

typedef struct x
{
int hashvalue;
char dictword[100];
char ascending[100];
struct x *next;
} node;

char *sortWord(char *);
//double fact(int);
void main()
{
FILE *fp1, *fp2;
char ch1;
while(ch1!='q')
{   
char *dictsort;
dictsort=(char *)malloc(100*sizeof(char));  
fp1=fopen("wordlist.txt", "r");
char ch;
int i=0;
char *sortedword;
int hashindex;
long int n;
printf("Please enter size of hashtable or press Ctrl+C to break:\n");
scanf("%ld", &n);


 node *hashtable[n];
 node *temp;
 char test1[50];
char *test;     
printf("Please enter the word to find anagrams for:\n");
scanf("%s", test1);
test=sortWord(test1);
int testhash=hashfunction(test);
printf("Hash value of word is %d\n", testhash);
for(i=0;i<1000000;i++)
{
    hashtable[i]=NULL;
}
temp=NULL;
while(!feof(fp1))
{   //printf("Seg fault here...\n");        
    //ch=getc(fp1);     
    fgets(dictsort, (100*sizeof(char)),fp1);
    //puts(dictsort);

    sortedword=(char *)malloc(sizeof(dictsort));
    sortedword = sortWord(dictsort);
    hashindex=hashfunction(sortedword);


    if(hashtable[hashindex]==NULL){ 

        hashtable[hashindex] = (node *)malloc(sizeof(node));
        strcpy(hashtable[hashindex]->dictword,dictsort);
        strcpy(hashtable[hashindex]->ascending,sortedword);
        hashtable[hashindex]->hashvalue=hashindex;
        hashtable[hashindex]->next=NULL;        
    }else{

        temp = (node *)malloc(sizeof(node));
        strcpy(temp->dictword,dictsort);
        strcpy(temp->ascending,sortedword);
        temp->hashvalue=hashindex;
        temp->next=hashtable[hashindex];
        hashtable[hashindex]=temp;
    //  free(temp);             
    }
    //printf("%s", hashtable[hashindex]->dictword);
    free(sortedword);

}

//for(i=0;i<100000;i++)
//{ 
    node *print;
    print=(node *)malloc(sizeof(node));
    print=hashtable[testhash];
    int chk;        

    while(print!=NULL)
    {
        chk=strcmp(print->ascending,test);
        if(chk==0)              
            {
                printf("%s\n", print->dictword);
                print=print->next;
            }   

        else
        print=print->next;
    }



    free(print);

}
}

int hashfunction(char *sw){

int a=0,i=0;
int k,b,c;
int div=1000000;
int blah;
int hv;     
for(i=0;sw[i]!='\0';i++){

    a=sw[i];
    //b=sw[i+1];
    //c=sw[i+2];        
    if(a!=10&&b!=10)
    {
        k=a*fact(i);
        b=k;            

        hv+=b;  
    }

}
hv=hv%div;  
return hv;

}

char *sortWord(char *s)
{
int c, d = 0, length;
char *pointer, *result, ch;
FILE *fp;
length = strlen(s);

result = (char*)malloc(length+1);

pointer = s;

for ( ch = 'a' ; ch <= 'z' ; ch++ )
{
        for ( c = 0 ; c < length ; c++ )
        {
            if ( *pointer == ch )
            {
                    *(result+d) = *pointer;
                    d++;
            }
        pointer++;
            }
    pointer = s;
}
*(result+d) = '\0';
char *z;
z=(char *)malloc(length+1);
strcpy(z, result);

//fp=fopen("sortedlist.txt", "a");
//fprintf(fp, "%s\n", s);

//fclose(fp);

free(result);

//puts(s);
//return result;
return z;   
//free(result); 


}

int fact(int num)
{
int i;
int val=1;
for(i=num+1;i>=1;i--)
{
    val=val*i;
}

return val%1000000;
}

Answer 1

Among a lot of other things:

 int hv;
 /* ... */
 hv+=b;

hv is never initialized. (Well as isn’t object b in the same function and as isn’t object ch1 is main function.)