如何返回二维数组

Question

char **splitWords(){
    
    FILE *inp;
    char **arr[1000][30];
    int i = 0;
    int word_count = 0;
    char c;
    int char_count = 0;

    inp = fopen("C:\\Users\\ksmcn\\Desktop\\free.txt", "r");
    
    while ((c = fgetc(inp)) != EOF) {
        if (c == ' ' || c == '\n') {
          //  printf("\n");

            arr[word_count][char_count] = '\0'; //Terminate the string
            char_count = 0; //Reset the counter.
            word_count++;
        }
        else {
            **arr[word_count][char_count] = c; 
        //  printf("%c",arr[word_count][char_count]);

             if (char_count < 99)
                 char_count++;
             else
                 char_count = 0;
        }   
    }
    fclose(inp);
    return **arr;
}

int main(int argc, char *argv[]) {
    
    char **array[1000][30];   
    char array = splitWords();
   
    return 0;
}

I want to return a two dimensional array using c programming. My splitWords function stores words as elements of an array and there is no issue about it. However I couldn't return my array to work in main function. Please help!

Answer 1

char **arr[1000][30];

You're declaring a 2D array of pointers to char pointers? I think you mean char arr[1000][30] . If you really do mean what this is, you are only initializing the space for a pointer, not the actual content of the pointer.

 inp = fopen("C:\\Users\\ksmcn\\Desktop\\free.txt", "r");

You should add a sanity check in case the file couldn't be opened. In other words, check if inp is NULL .

 arr[word_count][char_count] = '\0'; //Terminate the string

This will work if you declared arr as char[][] , but you declared it as **char[][] . See above.

 **arr[word_count][char_count] = c;

If you're declaring arr as char[][] , you need arr[word_count][char_count] . With your current declaration, this would work.

 if (char_count < 99)

Your array is only big enough to store 30 char s. Also, where's the check for if word_count exceeds 1000? Not to mention, if you reset char_count , then it will overwrite existing values!

 return **arr;

Dereferencing an uninitialized pointer is UB if I recall correctly. If your array were declared as char[][] , you'd need to do return arr .

 char **array[1000][30];

Why are you declaring something of type char **[][] when the function returns char ** ?

 char array = splitWords();

Why are you redefining array as type char ? This won't work! Not to mention (once again) splitWords() returns char ** , not char .