# How to make IDA properly generate array offsets?

**URL:** <https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425>\
**Category:** Support\
**Created:** [August 1, 2025, 9:26am UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425 "2025-08-01T09:26:45Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Xroft666](https://avatars.discourse-cdn.com/v4/letter/x/f04885/32.png) [@Xroft666](https://community.hex-rays.com/u/Xroft666)\
**Post date:** [August 1, 2025, 9:26am UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/1 "2025-08-01T09:26:45Z")

</div>

Assuming I am reversing a 32bit c++ structure that has an array at some offset. I have the data layout filled up in the Local Types, and for the most part it is working great when generating the pseudocode:

`element = myClass→array[stide * index];`

But very often (in the same subroutine) it also does this:

`element = myClass→gap0[stride * index]`  
`actualElement = element + the array offset;`

Both land at the same pointer, but the second variant is unreadable and make me falsely think that there is an array at the 0 offset (which I did believe at first and messed up my layouts 😅 ).

Is there a way to force or help IDA to prefer the proper indexing? It’s not that the layout is filled up wrong, since it does figure out 2 out of 4 structure fields.

Here is an actual example:

struct Render\_Service

{  
…  
00090178 TextureBuffer textures\_info[2048];  
…  
}

00000000 struct TextureBuffer // sizeof=0x10  
00000000 { // XREF: Render\_Service/r  
00000000 \_DWORD \*data;  
00000004 int width;  
00000008 int height;  
0000000C int flags;  
00000010 };

and a subroutine:

`int __thiscall sub_40B850(Render_Service *this, int a2, int *a3, int *a4, int *a5)`  
`{`  
` int width; // esi`  
` char *v6; // eax`  
` int v7; // ecx`  
` int result; // eax`

` width = this->textures_info[a2].width;`  
` v6 = &this->gap0[16 * a2];`  
` *a4 = this->textures_info[a2].height;`  
` v7 = *((_DWORD *)v6 + 147553); // ->textures_info[a2][3] = ->flags`  
` result = *((_DWORD *)v6 + 147550); // ->textures_info[a2][0] = ->data`  
` *a3 = width;`  
` *a5 = v7;`  
` return result;`

`}`

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<div class="post-metadata">

**Author:** ![revs](https://avatars.discourse-cdn.com/v4/letter/r/dc4da7/32.png) [@revs](https://community.hex-rays.com/u/revs)\
**Post date:** [August 1, 2025, 11:19am UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/2 "2025-08-01T11:19:16Z")

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set type of var “v6” as “Render\_Service \*”

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<div class="post-metadata">

**Author:** ![Xroft666](https://avatars.discourse-cdn.com/v4/letter/x/f04885/32.png) [@Xroft666](https://community.hex-rays.com/u/Xroft666)\
**Post date:** [August 1, 2025, 12:22pm UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/3 "2025-08-01T12:22:53Z")

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nice, thanks @revs ! worked out like a charm

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<div class="post-metadata">

**Author:** ![Morgan](https://avatars.discourse-cdn.com/v4/letter/m/0ea827/32.png) [@Morgan](https://community.hex-rays.com/u/Morgan)\
**Post date:** [August 1, 2025, 1:59pm UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/4 "2025-08-01T13:59:21Z")

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I think there’s indeed another array at +0 offset.

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<div class="post-metadata">

**Author:** ![Xroft666](https://avatars.discourse-cdn.com/v4/letter/x/f04885/32.png) [@Xroft666](https://community.hex-rays.com/u/Xroft666)\
**Post date:** [August 1, 2025, 2:25pm UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/5 "2025-08-01T14:25:17Z")

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i used to think that way, but then i would get conflicting data layout that overlaps and impossible to work out

the thing is though is that v6 (or similar pre-calculated variables) would never be used to directly access anything. It always used as an offset to an address, that just happens to be an array

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<div class="post-metadata">

**Author:** ![Xroft666](https://avatars.discourse-cdn.com/v4/letter/x/f04885/32.png) [@Xroft666](https://community.hex-rays.com/u/Xroft666)\
**Post date:** [August 1, 2025, 9:02pm UTC](https://community.hex-rays.com/t/how-to-make-ida-properly-generate-array-offsets/425/6 "2025-08-01T21:02:32Z")

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it still is a bit annoying, it maps correctly to the structure field, but instead of using the index, it just points to [0].

```auto
v8 = (Render_Service *)((char *)this + 16 * slot_idx);
width = v21;
height = v22;
v8->textures_info[0].width = v21;
this->textures_info[slot_idx].height = height;
v12 = mip_level;
v11 = mip_level == 0;
pixel_count = 0;
v8->textures_info[0].mip_level = mip_level;

```

without structure layout

```auto
v8 = &this[4 * slot_idx];
width = v21;
height = v22;
v8[147551] = v21;
this[4 * slot_idx + 147552] = height;
v12 = mip_level;
v11 = mip_level == 0;
pixel_count = 0;
v8[147553] = mip_level;

```

it looks like it can do `this[4 * slot_idx + 147552]`

but `v8[147551]` is confusing IDA

the code is so much readable tho, so its not that critical