I need to call a Julia function from C++ which returns a Vector of a custom type.

This doesn’t work, the vector has the correct number of elements but they are empty.

I have a Julia type and a Julia function as following :

```
type Point
x::Float64
y::Float64
z::Float64
end
Base.@ccallable function generate_vector_point()::Vector{Point}
size = 3
new_array = Vector{Point}()
resize!(new_array, size)
for i = 1:size
new_array[i] = Point(i + 0.1, i + 0.2, i + 0.3)
println(i, " : ", new_array[i])
end
return new_array
end
```

According to Julia doc, on the C side, I try to call the previous function as follows :

```
typedef struct{
double x;
double y;
double z;
} typepoint;
extern jl_value_t* generate_vector_point();
jl_value_t* retval;
typepoint *p;
retval = generate_vector_point();
if(jl_is_array(retval)) {
jl_value_t* el1type = (jl_value_t*)jl_array_eltype(retval);
int sz1 = jl_datatype_size(el1type);
printf("\n size: el1 %u\n",sz1);
printf("\n sizeof(typepoint) %u \n", sizeof(typepoint));
p = (typepoint*)jl_array_data(retval);
int ndimsret1 = jl_array_ndims(retval);
size_t sizeret1 = jl_array_dim(retval,0);
printf(" dims : %u \n",ndimsret1);
printf(" size(0): %u \n",sizeret1);
int idx1;
for (idx1 = 0; idx1 <= sizeret1 - 1; idx1++){
printf("pntr1 %u %p\n", idx1, &p[idx1]);
printf("pntr1.x %u %lf\n", idx1, p[idx1].x);
printf("pntr1.y %u %lf\n", idx1, p[idx1].y);
printf("pntr1.z %u %lf\n", idx1, p[idx1].z);
}
}
```

The output is the following :

1 : Point(1.1, 1.2, 1.3)

2 : Point(2.1, 2.2, 2.3)

3 : Point(3.1, 3.2, 3.3)size: el1 24

sizeof(typepoint) 24

dims : 1

size(0): 10pntr1 0 0x7fda971dceb0

pntr1.x 0 0.000000

pntr1.y 0 0.000000

pntr1.z 0 0.000000pntr1 1 0x7fda971dcec8

pntr1.x 1 0.000000

pntr1.y 1 0.000000

pntr1.z 1 0.000000pntr1 2 0x7fda971dcee0

pntr1.x 2 0.000000

pntr1.y 2 0.000000

pntr1.z 2 0.000000

NB : I have tried the same pattern with a Vector of Float64 and other base types and it works right.

What am I doing wrong ? Are there a better method to exchange this kind of data between Julia and C ?

Thank you for your help.

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