C Struct pointer issue

Question

I'm constructing a linked-list, and this is the list item Struct:

struct TListItemStruct
{
    void* Value;
    struct TListItemStruct* NextItem;
    struct TListItemStruct* PrevItem;
};
typedef struct TListItemStruct TListItem;
typedef TListItem* PListItem;

I use this in several function and it looks ok so far. However when I define the following variable:

PListItem item;

I get the following error:

error C2275: 'PListItem' : illegal use of this type as an expression

Why is that? What's wrong with defining a variable of type pointer to struct?

EDITS: This is more of the function. This doesn't work

BOOL RemoveItem(PListItem item)
{
    // Verify
    if (item == NULL)
    {
        return FALSE;
    }
    // Get prev and next items
    PListItem prev;
    prev = item->PrevItem;
    //PListItem next = (PListItem)(item->NextItem);
 ...

However this works:

BOOL RemoveItem(PListItem item)
{
    PListItem prev;
    // Verify
    if (item == NULL)
    {
        return FALSE;
    }
    // Get prev and next items
    prev = item->PrevItem;
    //PListItem next = (PListItem)(item->NextItem);
 ...

I'm using VS2012, maybe it's a standard thing? to declare vars in the beginning of the function?

Your problem might be somewhere else in the code causing this specific variable declaration to be parsed incorrectly. — Jason, Nov 19 '12 at 19:00
This is a C, C++ problem. The pointer "this" doesn't exist on C, which compiler are you using? What extension is your file? Can you show some more code? — imreal, Nov 19 '12 at 19:04
Seems like it's because I've declared the vars in the function body and not right on start. Is this a C issue? — Nitay, Nov 19 '12 at 19:09
Yes, before C99 I think, try moving them to the top of the function. — imreal, Nov 19 '12 at 19:11
http://stackoverflow.com/questions/9903582/error-c2275-illegal-use-of-this-type-as-an-expression — imreal, Nov 19 '12 at 19:18

iabdalkader · Accepted Answer · 2012-11-19T19:18:15.323

2

MSVC uses C89, it does not support C99, so you need to either declare all variables at the beginning of your function or compile as C++.

edited Nov 19 '12 at 19:18

answered Nov 19 '12 at 19:04

iabdalkader

17,009
4
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@RavindraBagale `this` is a keyword in C++ – iabdalkader Nov 19 '12 at 19:08
@Cicada it is still a possibility, no ? I've added the error from MSDN anyway – iabdalkader Nov 19 '12 at 19:09
@mux:in question that was not a keyword, it showing because of SO's parser – Ravindra Bagale Nov 19 '12 at 19:11
@Cicada yes I get the syntax highlighting thing :) was just saying, anyway I removed that and just left the example – iabdalkader Nov 19 '12 at 19:12

score 1 · Answer 2 · answered Nov 19 '12 at 19:18

1

In C89 (which is supported by Visual Studio 2012) you have to declare variables at the beginning of the scope. That's why your latter example works fine.

answered Nov 19 '12 at 19:18

pm007

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C Struct pointer issue

2 Answers2