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structure initialization error

Started by econoy Dec 17, 2004 at 10:01 AM 4 replies 600+ views

Original Post

Dec 17, 2004 at 10:01 AM

I give these codes:


#include<stdio.h>
struct a
{
 int b;
 char c;
};
struct d
{
 int id;
 struct a xx[2];
};
void main(void)
{

struct d*  structptr;
struct d example;
structptr=&example
structptr->id=1;
structptr->xx[0]={2,'x'};/*error here*/
structptr->xx[1]={3,'y'};/*error here*/

/*if I use these codes ,it will have no error:
structptr->xx[0].b=2;
structptr->xx[0].c='x';
*/

printf("%d,%d,%c",structptr->id,structptr->xx[0].b,structptr->xx[0].c);
}

My compiler is Turbo C,why did it happen?

Morbo

Dec 17, 2004 at 10:11 AM

Neither C nor C++ allow initialization of structures. Even if they did, you can perform initialization when a variable is declared. So this works:

int var[5] = {1,2,3,4,5};

But this doesn't:

int var[5];
var = {1,2,3,4,5};

With structs you're better off to create constructors if you want to perform initialization.

econoy

Author

econoy

Dec 17, 2004 at 10:26 AM

thx,mabe I used an ill-suited word 'initialization'
I just want to know if I can only use these:
structptr->xx[0].b=2;
structptr->xx[0].c='x';

but not these:
structptr->xx[0]={2,'x'};

Miserable

Dec 17, 2004 at 10:43 AM

struct initialisers only work at the point of declaration.

struct foo {    int x;    int y;};void bar() {    foo f = { 1, 2 }; // good    foo g;    g = { 3, 4 }; // bad}

Zahlman

257

Zahlman

Dec 17, 2004 at 2:06 PM

And thus:

struct d example = { 1, // id                     { {2, 'x'}, // x[0]                       {3, 'y'}, // x[1]                     } // x                   };// should work, as far as I know

econoy

Author

econoy

Dec 17, 2004 at 8:05 PM

Thanks!^-^
I think I get it.

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