C initialize pointer to array in array initializator

Question

I need to initialize array of this structure:

struct a {

   int *a;
   int *b;
   int count;
};

My code looks like this;

struct a[] = 
{
  {{1,2},{3,4}, 2},
  {{1},{3}, 1}
};

This will compile, but segfaults, when program tries to access first element of field.

Because you haven't allocated memory for the members a and b. — P.P
– P.P, Commented Oct 16, 2014 at 6:54
This will not compile ... This is not valid C at all. Please come back when you have real code that doesn't work. Voting to close. — Jens Gustedt
– Jens Gustedt, Commented Oct 16, 2014 at 6:58
I'm with @JensGustedt. Enable warnings in your compiler and you will immediately see this code is really, really wrong. gcc -Wall -Wextra -Werror for example. — John Zwinck
– John Zwinck, Commented Oct 16, 2014 at 7:00

BLUEPIXY · Accepted Answer · 2014-10-16 07:06:16Z

2

struct a a[] = 
{
  {(int[]){1,2},(int[]){3,4}, 2},
  {(int[]){1},(int[]){3}, 1}
};

answered Oct 16, 2014 at 7:06

BLUEPIXY

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Comments

Mohit Jain · Accepted Answer · 2014-10-16 07:22:38Z

1

You should use something like (Adding to BLUEPIXY's answer)

static int arr1[] = {1, 2};
static int arr2[] = {3, 4};
static int arr3[] = {1};
static int arr4[] = {3};

struct a a[] = 
{
  {arr1, arr2, 2},
  {arr3, arr4, 1}
};

Live code here

Further reading: equivalence of pointers and arrays in C

edited Oct 16, 2014 at 7:22

answered Oct 16, 2014 at 7:17

Mohit Jain

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1 Comment

glglgl Over a year ago

struct a[] = ...? Really?

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