assigning values of 2d array inside a struct

Question

I have the following error expected ':', ',', ';', '}' or 'attribute' before '=' token

struct arrap{
 char p[6][6] = {
    {' ',' ',' ',' ',' ',' '},
    {' ',' ',' ',' ',' ',' '},
    {' ',' ',' ',' ',' ',' '},
    {' ',' ',' ',' ',' ',' '},
    {' ',' ',' ',' ',' ',' '},
    {' ',' ',' ',' ',' ',' '}
    };
};

it seems that it doesnt work any other ways to initialize the values of the 2d array inside a structure?

ouah · Answer 1 · 2013-12-15T16:08:18.693

3

This is the correct way:

struct arrap {
     char p[6][6];
} a = {{{' ',' ',' ',' ',' ',' '},
        {' ',' ',' ',' ',' ',' '},
        {' ',' ',' ',' ',' ',' '},
        {' ',' ',' ',' ',' ',' '},
        {' ',' ',' ',' ',' ',' '},
        {' ',' ',' ',' ',' ',' '}
      }};

It declares the type struct arrap and declares an object a of type struct arrap with the initializers you wanted.

You cannot set default initializer values for a type in C but you can initialize an object at declaration time.

edited Dec 15 '13 at 16:08

answered Dec 15 '13 at 16:02

ouah

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it answered my question but int main(){ int x,i; struct arrayp p; for(i = 0;i<5;i++){ for(x = 0; x<5;x++){ printf("%c\n",p.p[i][x]); } } it prints characters that is not ' ' why is it? – PNC Dec 15 '13 at 16:12
@PNC except that you have to use `6` instead of `5` in your loops, this looks fine to me. Remember that `' '` are white spaces. Otherwise, please show the whole program. – ouah Dec 15 '13 at 16:18

score 2 · Answer 2 · answered Dec 15 '13 at 16:00

You can't assign to an array inside a structure. You have to initialize it when you create an instance of the structure.

The easiest way is probably to have a constant static array, and use e.g. memcpy to copy it:

static const char p_template[6][6] = { ... };

...

struct arrap ap;
memcpy(ap.p, p_template, sizeof(p_template));

score 1 · Answer 3 · answered Dec 15 '13 at 16:09

1

Quick & Dirty:

struct arrap s;
memset(&s, ' ', sizeof(s.p));

This works as the address of the 1^st member of a struct is guaranteed to be the same address of the struct itself.

answered Dec 15 '13 at 16:09

alk

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assigning values of 2d array inside a struct

3 Answers3