how to initialize nested arrays

Question

What is the correct syntax to initialize the following 2 level of nested arrays ?

z3 src # cat tc.c
#include <stdio.h>

typedef struct level1_t {
        char                           var[15];
        int                            value;
} level1_t;

typedef struct level2_t {
    level1_t     data[3];
} level2_t;

level2_t level2[1] = {
                [0]={
                        [0]={"one",1},
                        [1]={"two",2},
                        [2]={"three",3}
                }
};

int main() {

        printf("%s\n",level2[0].data[1].var);
}
z3 src # gcc -ggdb -o tc tc.c
tc.c:14:4: error: array index in non-array initializer
tc.c:14:4: error: (near initialization for 'level2[0]')
tc.c:15:4: error: array index in non-array initializer
tc.c:15:4: error: (near initialization for 'level2[0]')
tc.c:15:4: error: extra brace group at end of initializer
tc.c:15:4: error: (near initialization for 'level2[0]')
tc.c:15:4: warning: excess elements in struct initializer
tc.c:15:4: warning: (near initialization for 'level2[0]')
tc.c:16:4: error: array index in non-array initializer
tc.c:16:4: error: (near initialization for 'level2[0]')
tc.c:16:4: error: extra brace group at end of initializer
tc.c:16:4: error: (near initialization for 'level2[0]')
tc.c:16:4: warning: excess elements in struct initializer
tc.c:16:4: warning: (near initialization for 'level2[0]')
z3 src #

Just as a warning, this syntax is only available in C ISO C99 (not C++). — Mark Lakata
– Mark Lakata, Commented Apr 10, 2014 at 17:14

pNre · Accepted Answer · 2014-04-10 17:54:21Z

4

Change

level2_t level2[1] = {
                [0]={
                        [0]={"one",1},
                        [1]={"two",2},
                        [2]={"three",3}
                }
};

to

level2_t level2[1] = {
                [0].data = {
                        [0]={"one",1},
                        [1]={"two",2},
                        [2]={"three",3}
                }
};

Right now you're trying to initialize the structure as an array, while you need to initialize the data field.

As you asked in comments here's how to do the same thing without indexes:

level2_t level2[] = {
    {
        .data = {
            {"one", 1},
            {"two", 2},
            {"three", 3}
        }
    }
};

edited Apr 10, 2014 at 17:54

answered Apr 10, 2014 at 16:57

pNre

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1 Comment

Nulik Over a year ago

by any chance do you know what would be the syntax without the square brackets [0],[1],[2] at all ?

Mahonri Moriancumer · Accepted Answer · 2014-04-10 17:01:01Z

0

level2_t level2 =
{
   {"one, 1},
   {"two, 2},
   {"three", 3}
};

answered Apr 10, 2014 at 17:01

Mahonri Moriancumer

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2 Comments

Mark Lakata Over a year ago

This is a better way of initializing the entire data structure, as it is more portable.

Nulik Over a year ago

yes, but it doesn't detail the nesting, also it misses fixed size of the array, what if I make a syntax error and initalize larger structure than I should?

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