Segmentation fault：打印“Dictionary”内容时出现11

Question

I've been trying to create a dictionary of words and their definitions(sort of Oxford English Dictionary). So far, I've finished half of the job:

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

typedef struct{

    char wordInDictionary[32];
    int numberOfMeanings;
    char *wordDefinitions[10];

}Entry; //struct that describes a single entry in the dictionary

typedef struct{

    int entries;
    Entry* arrayOfEntries[100];

}Dictionary; //dictionary itself

Dictionary createDictionary(){

    Dictionary emptyDictionary;

    emptyDictionary.entries = 0;

    int i,j;

    for(i=0;i<100;i++){
        emptyDictionary.arrayOfEntries[i] = malloc(sizeof(Entry));
        emptyDictionary.arrayOfEntries[i]->numberOfMeanings = 0;
        strcpy(emptyDictionary.arrayOfEntries[i]->wordInDictionary, "");
        for(j=0;j<10;j++){
            emptyDictionary.arrayOfEntries[i]->wordDefinitions[j] = 
            malloc(500*sizeof(char));

            strcpy(emptyDictionary.arrayOfEntries[i]->wordDefinitions[j], "");
        }

    }

    return emptyDictionary; //created empty dictionary with 0 entries and empty content
}

Entry* searchWord(char word[], Dictionary *dict){

    Entry* foundWord;

    int i;

    for(i=0;i<100;i++){
        if(strcmp(dict->arrayOfEntries[i]->wordInDictionary, word) != 0){
            foundWord = NULL;
        }else{
            foundWord = dict->arrayOfEntries[i];
            break;
        }
    }

    return foundWord; //searches for a given word and returns NULL, if word is not found, or pointer to entry in the dictionary that corresponds to word, if word is found.

}

int addDefinition(char word[], char meaning[], Dictionary *dict){

    Entry* foundEntry = searchWord(word, dict);

    int returnNumber;

    if((foundEntry == NULL || strcmp(foundEntry->wordInDictionary, word) != 0) 
            && dict->entries < sizeof(dict->arrayOfEntries)/sizeof(dict->arrayOfEntries[0])){

        Entry* newEntry = malloc(sizeof(Entry)); //allocating space if searched word is not found in dictionary

        strcpy(newEntry->wordInDictionary, word); //now there is a new word in the dictionary
        newEntry->numberOfMeanings = 0; //but the new word has 0 meanings

        dict->arrayOfEntries[dict->entries++] = newEntry;

        if(newEntry->numberOfMeanings<10){ 
            newEntry->wordDefinitions[newEntry->numberOfMeanings] = malloc(500*sizeof(char));
            strcpy(newEntry->wordDefinitions[newEntry->numberOfMeanings], meaning); //new word now has a new meaning since its meanings' amount is less than 10(which is max)
        }

        int oldNumberOfMeanings = newEntry->numberOfMeanings;
        int newNumberOfMeanings = oldNumberOfMeanings + 1;

        if(newNumberOfMeanings>oldNumberOfMeanings){
            returnNumber = 2; //returns 2 if both new entry and new definition were added into the dictionary
        }

        newEntry->numberOfMeanings++;

    }else if((foundEntry != NULL || strcmp(foundEntry->wordInDictionary, word) == 0) 
            && dict->entries < sizeof(dict->arrayOfEntries)/sizeof(dict->arrayOfEntries[0])){

        if(foundEntry->numberOfMeanings<10){
            foundEntry->wordDefinitions[foundEntry->numberOfMeanings] = malloc(500*sizeof(char));
            strcpy(foundEntry->wordDefinitions[foundEntry->numberOfMeanings], meaning);
        }

        int oldNumberOfMeanings = foundEntry->numberOfMeanings;
        int newNumberOfMeanings = oldNumberOfMeanings + 1;

        if(newNumberOfMeanings == oldNumberOfMeanings){
            returnNumber = 0; //returns 0 if no new entry and no new meaning are added to already found one
        }else if(newNumberOfMeanings > oldNumberOfMeanings){
            returnNumber = 1; //returns 1 if no new entry and one new meaning are added to already found one
        }

        foundEntry->numberOfMeanings++;
    }

    return returnNumber;
}

So this vague piece of code describes my program. But the problem itself occurs when I test the code in main() :

int main(void){

    Entry* entryPtr;

    Dictionary dict = createDictionary();

    entryPtr = searchWord("include", &dict);

    if(entryPtr != NULL){
        printf("\nWord found: 'include'");
    }else{
        printf("\nWord 'include' is not found in the dictionary.");
    }

    int count;

    count = addDefinition("include", "(verb) def1", &dict);
    count = addDefinition("assist", "(verb) def2", &dict);
    count = addDefinition("house", "(noun) def3", &dict);
    count = addDefinition("camera", "(noun) def4", &dict);
    count = addDefinition("valid", "(adjective) def5", &dict);

    printf("\nLast count: %i", count);

    int i, j;

    for(i=0;i<100;i++){
        if(strcmp(dict.arrayOfEntries[i]->wordInDictionary, "")!=0){
            printf("\n\t%i. %s", i+1, dict.arrayOfEntries[i]->wordInDictionary);
        }
        for(j=0;j<10;j++){
            if(strcmp(dict.arrayOfEntries[i]->wordDefinitions[j], "")!=0){
                printf("\n\t\t%i.%i. %s\n", i+1, j+1, dict.arrayOfEntries[i]->wordDefinitions[j]);
            }
        }
    }

    entryPtr = searchWord ("exam", &dict);
    if (entryPtr != NULL) {
        printf("\nWord found: 'exam'");
    } else {
        printf("\nWord 'exam' is not found in the dictionary.");
    }

    entryPtr = searchWord ("include", &dict);
    if (entryPtr != NULL) {
        printf("\nWord found: 'include'");
    } else {
        printf("\nWord 'include' is not found in the dictionary.");
    }

    count = addDefinition ("house", "(adjective) def6", &dict);
    count = addDefinition ("house", "(adjective) def7", &dict);
    count = addDefinition ("house", "(adjective) def8", &dict);

    printf("\n\nThe the value returned by the last addition: is %i.", count);

}

What the output gives is:

Word 'include' is not found in the dictionary.
Last count: 2
        1. include
                1.1. (verb) def1
Segmentation fault: 11

I changed the condition in nested for loops in main() as follows:

for(i=0;i<5;i++){
        if(strcmp(dict.arrayOfEntries[i]->wordInDictionary, "")!=0){
            printf("\n\t%i. %s", i+1, dict.arrayOfEntries[i]->wordInDictionary);
        }
        for(j=0;j<1;j++){
            if(strcmp(dict.arrayOfEntries[i]->wordDefinitions[j], "")!=0){
                printf("\n\t\t%i.%i. %s\n", i+1, j+1, dict.arrayOfEntries[i]->wordDefinitions[j]);
            }
        }
}

Then it showed the right content, though it is not what it should be like. Instead, it should work for all the entries in the dictionary, not first 5.

I've tried doing debugging many times and investigate it myself but still could not find the solution. Any hints to solve the possible problem(-s)?

PS I run the program on VS Code, macOS, GCC.

Answer 1

The issue is in line

if(strcmp(dict.arrayOfEntries[i]->wordDefinitions[j], "")!=0)

It doesn't check for valid dict.arrayOfEntries[i]->wordDefinitions[j] pointer. Something like this:

if(dict.arrayOfEntries[i]->wordDefinitions[j] && strcmp(dict.arrayOfEntries[i]->wordDefinitions[j], "")!=0)

Beside that, I think you are using malloc badly, you are creating at runtime a whole empty dictionary in createDictionary and then creating new entries in addDefinition and adding them like this:

dict->arrayOfEntries[dict->entries++] = newEntry;

This newEntry replaces the old pointer and it doesn't event delete it, this is a memory leak, and beside that newEntry is not fully initialized, and that's the main reason of the segmentation fault.