2D character array contents getting overwritten

Question

I am trying to read a string and reverse the words in the string., but the content of the strings is getting overwritten and I am getting garbage values for the first few strings in the 2D array. Eg when I print the words in reverse order at the end of the function, I am getting junk for the first few strings. What am I doing wrong?

void reverseWords(char *s) {
    char** words;
    int word_count = 0;

    /*Create an array of all the words that appear in the string*/
    const char *delim = " ";
    char *token;
    token = strtok(s, delim);
    while(token != NULL){
        word_count++;
        words = realloc(words, word_count * sizeof(char));
        if(words == NULL){
            printf("malloc failed\n");
            exit(0);
        }
        words[word_count - 1] = strdup(token);
        token = strtok(NULL, delim);
    }

    /*Traverse the list backwards and check the words*/
    int count = word_count;
    while(count > 0){
        printf("%d %s\n",count - 1, words[count - 1]);
        count--;
    }
}

Answer 1

You need to change that line:

words = realloc(words, word_count * sizeof(char));

You allocate char s, that is, single characters. You want pointers. Therefore, use this:

words = realloc(words, word_count * sizeof(char*));

Also, as @ Snild Dolkow stated, initialize words to NULL . Otherwise realloc will attempt to use the undefined value of words as the memory to reallocate. Further information at man realloc .

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Notes:

• You should free the memory returned to you by strdup after usage