Reference inside node?

Question

I'm trying to build a BST. My struct;

typedef struct node{
    int charSize;
    char english[30];
    char span[40];
    struct node *left;
    struct node *right;
} BST;

i'm trying to compare two character arrays. In Xcode, it does not give me any warning using the following lines to compare the arrays, but i'm sure its wrong and was wondering why is it not giving me an error.

if (head->english <= head2->english)
    printf("headOne is smaller or equal");
else
    printf("headOne is Bigger");

Just because something is legal doesn't mean it is what you want to do. — Scott Hunter, Dec 03 '16 at 00:42
http://stackoverflow.com/questions/1461432/what-is-array-decaying — Michael Albers, Dec 03 '16 at 00:43
@ScottHunter i understand but i want to understand why is it legal. — STOPIMACODER, Dec 03 '16 at 00:57

artm · Accepted Answer · 2016-12-03T00:51:37.493

1

if (head->english <= head2->english)

why is it not giving me an error.

Because it's legal to compare pointers head->english and head2->english. Remember array name (character array or any other type of array) is pointer to the first element. So here you are actually comparing those two pointers.

Of course that is not what you want, you need strcmp to compare C strings.

edited Dec 03 '16 at 00:51

answered Dec 03 '16 at 00:45

artm

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So in this sense i'm comparing the first element of the array. The first element of both arrays are identical, so why is it not printing "headOne is smaller or equal" ? – STOPIMACODER Dec 03 '16 at 01:04
they are pointers to the first elements, NOT the first elements themselves – artm Dec 03 '16 at 01:05
Thank you for your help! – STOPIMACODER Dec 03 '16 at 01:07

Bruno Nascimento · Answer 2 · 2016-12-03T01:57:27.937

1

if (head->english <= head2->english) will compare the value of the pointers, meaning the addresses they point to. Not the contents of the memory addresses.

strcmp() will actually compare the individual values of the characters in the string, so it's more useful for sorting.

If you're trying to determine which string is lengthier you should use if (strlen(head->english) <= strlen(head2->english))

edited Dec 03 '16 at 01:57

answered Dec 03 '16 at 01:14

Bruno Nascimento

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Reference inside node?

2 Answers2