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PODeclaring a struct (that's already been typedef'd) within another struct?
 

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  1. PODeclaring a struct (that's already been typedef'd) within another struct?
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    <p>My understanding of C is that there are two separate namespaces, one for tags (such as for structs) and one for all other variables (including structs). Using typedef before a struct definition will then treat the struct variable as a type, so if you use </p> <pre><code>struct car_part {/* Code Here */} CarPart; </code></pre> <p>(where CarPart is optional)<br> you'd have to use </p> <pre><code>struct car_part engine; </code></pre> <p>to declare a car part.<br> Whereas if you used a typedef with</p> <pre><code>typedef car_part {/* Code Here */} CarPart; </code></pre> <p>you can now use</p> <pre><code>CarPart engine; </code></pre> <p>instead.</p> <pre><code>typedef struct tag {/* Code here */} struct_name; </code></pre> <p>1) Is there any difference between declaring the actual variable before or after the block code? i.e.</p> <pre><code>typedef struct tag struct_name { /* Code here */ }; </code></pre> <p>vs</p> <pre><code>typedef struct tag { /* Code here*/ } struct_name; </code></pre> <p>2) Are there ever any advantages to not using typedef for a struct definition, even if you won't declare another struct variable of that type?</p> <p>3) The following code says that there's a syntax error C2061 with the identifier Node, but I don't see anything wrong with it. I tried adding the keyword struct before each element declaration, but that only gave more errors. Any thoughts?</p> <pre><code>typedef struct Ticket { char customer_name[20]; int ticket_number; } Ticket; typedef struct Node { Ticket ticket_info; Node *next; Node *previous; } Node; typedef struct Queue { Ticket *front; Ticket *rear; int queue_count; } Queue; </code></pre> <p>edit: fixed first two lines of code to explicitly state where the element declarations should be.</p>
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    1. USAleyha
    1. USAleyha
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    1. COI have the habit of naming my `struct` with a `_st` suffix, so `struct node_st { /*fields*/ };` and `typedef struct node_st Node;`
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      1. PODeclaring a struct (that's already been typedef'd) within another struct?
      1. USBasile Starynkevitch
    2. COYour very first line of code is invalid. What would you expect `struct car_part CarPart;` to do, in words? gcc just gives me an error "storage size of 'CarPart' isn't known" when I compile a program where that is the first line.
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      1. PODeclaring a struct (that's already been typedef'd) within another struct?
      1. USDavid Grayson
    3. CO@David Sorry, meant to put code between car_part and CarPart like in the other code. That'd be where the element declaration would go.
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      1. USAleyha
 

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