Program received signal SIGBUS, Bus error.

[bubbles19518]

I have my c project which works fine and compiles fine on my home machine (MacBook Pro Mac OSX). When I upload it to my school server and compile it there it compiles but I get a bus error when I try option 2. My program gets graded on the school server, so its important I get it to compile lol. My school server is some sort of linux machine, not sure which.

I think the problem code is here:

						head->paths[letter] = (node*)malloc(sizeof(node));
						head->paths[letter]->c = word[i];
						head->paths[letter]->setn = malloc((strlen(head->setn) +2) * sizeof(char));
						strcpy(head->paths[letter]->setn,head->setn);
						head->paths[letter]->setn[strlen(head->setn)] = word[i];
						head->paths[letter]->setn[strlen(head->setn)+1] = '\0';						
						head->paths[letter]->isWord = 0;
						head = head->paths[letter];

Any help is greatly appreciated.

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

struct node {
	char c;	// the current char
	char *setn; //total
	int isWord;	/* To check if this is a valid word to be written into dict.txt,
			   0 is false, 1 is true*/
	struct node *paths[26];	// A subexpression can be followed by any of the 26 characters
};

typedef struct node node;

void suggest(node *n);

int main() {
	int choice,i,letter,j;
	int startWord = 0;
	char word[100];
	FILE *fp;
	char c;
	char cc[2];
	cc[1] = '\0';
	node *head = (node *) malloc(sizeof(node));
	node *cur = (node *) malloc(sizeof(node));
	node *paths[26];
	
	for(i = 0;i<26;i++) {
		paths[i] = (node *) malloc(sizeof(node));
		paths[i]->c = (char)(i+65);
		paths[i]->setn = malloc(2);
		paths[i]->setn[0] = '\0';
		cc[0] = (char)(i+65);
		paths[i]->setn = strcat(paths[i]->setn,cc);
		paths[i]->isWord = 0;
	} //create tree root
	
	while(1) {
		printf("\n=============================================================================\n\n");
		printf("1.	Create a dictionary\n");
		printf("2.	Add a word\n");
		printf("3.	Suggest a word\n");
		printf("4.	Spell check\n");
		printf("5.	Save the dictionary\n");
		printf("6.	Exit\n\n");
		printf("Enter choice: ");
		scanf("%d",&choice);
		if(choice == 1) {
			//Build Dictionary
			fp = fopen("dict.txt","r");
			while((c = fgetc(fp)) != EOF) {
				letter = (((int)c)-65);
				if(c == '#') {
					if(startWord == 0) {
						startWord = 1;
						head = 0;
					}
					else {
						startWord = 0;	
						head->isWord = 1;
						i = 0;
					}
				}
				else if((int)c >= 65 && (int)c <= 90) {
					if(head == 0) {
						head = paths[letter];
					}
					else {
						if(head->paths[letter] == 0) {
							head->paths[letter] = (node *)malloc(sizeof(node));
							head->paths[letter]->c = c;
							head->paths[letter]->setn = malloc((strlen(head->setn) +2) * sizeof(char));
							strcpy(head->paths[letter]->setn,head->setn);
							head->paths[letter]->setn[strlen(head->setn)] = c;
							head->paths[letter]->setn[strlen(head->setn)+1] = '\0';
							head->paths[letter]->isWord = 0;
							head = head->paths[letter];
						}
						else {
							head = head->paths[letter];
						}
					}
				}
			}
			printf("Dictionary has been created.");
			fclose(fp);
			head = 0;
		}
		if(choice == 2) {
			//Add Word
			printf("Enter word: ");
			scanf("%s",word);
			j = 0;
			while(word[j] != '\0')
				{j++;} //length
			for(i = 0;i<j;i++) {
				letter = (((int)word[i])-65);
				if(head == 0) {
					head = paths[letter];	
				}
				else {
					if(head->paths[letter] == 0) {
						head->paths[letter] = (node*)malloc(sizeof(node));
						head->paths[letter]->c = word[i];
						head->paths[letter]->setn = malloc((strlen(head->setn) +2) * sizeof(char));
						strcpy(head->paths[letter]->setn,head->setn);
						head->paths[letter]->setn[strlen(head->setn)] = word[i];
						head->paths[letter]->setn[strlen(head->setn)+1] = '\0';						
						head->paths[letter]->isWord = 0;
						head = head->paths[letter];
					}
					else {
						head = head->paths[letter];	
					}
				}
			}
			head->isWord = 1;
			printf("New word \"%s\" added to the dictionary",word);
			head = 0;
		}
		if(choice == 3) {
			//Suggest a word	
			printf("Enter subexpression: ");
			scanf("%s",word);
			j=0;
			while(word[j] != '\0') 
				{j++;} //length
			for(i = 0;i<j;i++) {
				letter = (((int)word[i])-65);
				if(head == 0) {
					head = paths[letter];	
				}
				else {
					head = head->paths[letter];	
				}
			}
			printf("The suggested words are: ");
			suggest(head);
			head = 0;
		}
		if(choice == 4) {
			//Spell Check
			printf("Enter string: ");
			scanf("%s",word);
			j=0;                 
			while (word[j] != '\0') 
				{j++;} //string length
			for(i = 0;i<j;i++) {
				letter = (((int)word[i])-65);
				if(head == 0) {
					head = paths[letter];
				}
				else {
					if(head->paths[letter] == 0) {
						printf("Result: Spelling is incorrect.");
						break;
					}
					else {
						head = head->paths[letter];
					}
				}
			}
			if(head->c == word[i-1]) {
				printf("Result: Spelling is correct.");	
			}
			head = 0;	
		}
		if(choice == 5) {
			//Save the Dictionary	
		}
		if(choice == 6) {
			//Exit
			break;
		}
	}
}

void suggest(node *n) {
	int i;
	if(n->isWord == 1) {
		printf("%s, ",n->setn);	
	}
	for(i = 0;i<26;i++) {
		if(n->paths[i] != 0) {
			suggest(n->paths[i]);	
		}
	}
}

[newb16]

Use strlen() instead of home-made loop. sizeof(char) is 1 by definition.

Compile it at school in debug mode and run under gdb until it crashes ( or run gdb providing dumped core ), then post relevant info ( line number, stack trace ) here.

[vmpstr]

I see two (and a half) things that I would fix.

The half is that half of your malloc returns are cast and have are not. Pick one (not casting malloc is the correct thing to do in C).

Other than that,

1. You might want to check if letter is negative before you index into an array using it. I'm referring to character-65 calculation. There are plenty of characters that will cause that expression to be negative.

2. You might want to switch the order of lines 108 and 109. Reason being, once you have overwritten the nul terminator on line 108, strlen on lines 109 loses much of its correctness. If there was only one nul terminator, then it will probably cause the error you are seeing.