为什么打印二维字符数组会产生垃圾值？

Question

I am implementing a function that prints a 2D array of characters only using a double-pointer and pointer notation. When I run the code, it prints a bunch of garbage values in the format I want instead of the correct characters.

My professor instructed me not to use arr[row][col], instead, I must access it using ( (arr+i)+j) or similar

This is a project for a class and I can't change any of the code outside of this function. The characters are meant to be formatted like a word search puzzle. The arguments passed to my function are char** arr, int size .

This is my function:

for(int i = 0; i < size; i++){
    printf("%c %c %c %c %c %c %c %c %c %c %c %c %c %c %c\n", *(arr+i), *(arr+i)+1, *(arr+i)+2, *(arr+i)+3, *(arr+i)+4, *(arr+i)+5, *(arr+i)+6, * 
(arr+i)+7, *(arr+i)+8, *(arr+i)+9, *(arr+i)+10, *(arr+i)+11, *(arr+i)+12, *(arr+i)+13, *(arr+i)+14 );   }

Expected output:

W D B M J Q D B C J N Q P T I
I R Z U X U Z E A O I O R T N
M N Z P L R N H L Y L X H M D
M Y E K A I D P I U L Y O W I
A O A B A R K U F V I H L A A
L O N M R X K I O J N A V R N
A E P T A A R A R T O W A I A
S U C Z A U S I N A I A L Z V
K O T A O N R K I S S I A O N
A H X S V K A I A E A I B N E
U D S X N X C C D W G S A A V
O I S D W L E J N J T X M H A
M O X W T N H Q D X O Q A Q D
R U U V G E O R G I A Q V D A
V F L O R I D A L G L W O X N

Actual output:

░ ▒ ▓ │ ┤ ╡ ╢ ╖ ╕ ╣ ║ ╗ ╝ ╜ ╛
≡ ± ≥ ≤ ⌠ ⌡ ÷ ≈ ° ∙ · √ ⁿ ² ■

0 1 2 3 4 5 6 7 8 9 : ; < = >
P Q R S T U V W X Y Z [ \ ] ^
p q r s t u v w x y z { | } ~
É æ Æ ô ö ò û ù ÿ Ö Ü ¢ £ ¥ ₧
░ ▒ ▓ │ ┤ ╡ ╢ ╖ ╕ ╣ ║ ╗ ╝ ╜ ╛
╨ ╤ ╥ ╙ ╘ ╒ ╓ ╫ ╪ ┘ ┌ █ ▄ ▌ ▐
≡ ± ≥ ≤ ⌠ ⌡ ÷ ≈ ° ∙ · √ ⁿ ² ■

0 1 2 3 4 5 6 7 8 9 : ; < = >
P Q R S T U V W X Y Z [ \ ] ^
└ ┴ ┬ ├ ─ ┼ ╞ ╟ ╚ ╔ ╩ ╦ ╠ ═ ╬
` a b c d e f g h i j k l m n

Answer 1

If arr is really a char** , then you need to dereference twice to get a char .

So, in your statement, arr+i is another char** , pointing at a char* i steps further along from the one arr points at. Hopefully arr points at the beginning of an array of char* at least size long.

Now *(arr+i) dereferences it, fetching the char* pointed to by arr+i , giving you a char* .

Now *(arr+i)+7 , for example, is another char* , pointing at a char 7 steps further along from the one *(arr+i) points at. Hopefully *(arr+i) points at the beginning of an array of char at least 15 long.

But you don't dereference it, so you're attempting to print the value of the pointer (ie the address it holds), not the value it points to (the char ).

Try *(*(arr+i)+7) .