CODEWITHSUNDEEP
c
Md. Ariful Islam
Md. Ariful Islam

Reputation: 3

What does the compiler with the code and why the nested struct throwing error?

typedef struct node{
int val;
node *next;
} node;
node *start;

Here this code throws an error on line 3. But if I modify it like this,

typedef struct node{
int val;
struct node *next;
} node;
node *start;

This is correct? But why the compiler do so? And how the compiler execute it?

Upvotes: 0

Views: 43

Answers (1)

Tom Karzes
Tom Karzes

Reputation: 24052

The problem is that the node type doesn't exist until after the end of the typedef declaration, so it cannot be referenced in the structure body. But the structure tag in struct node can.

My preferred solution is to declare the typedef using a forward reference to the structure definition, then define the structure in a second declaration. The advantage is that it allows the typedef name to be used inside the structure defintion. It looks like this:

typedef struct node node;
struct node {
    int val;
    node *next;
};

This allows you to use the typedef name node consistently in all declarations, including the ones inside the structure definition.

Upvotes: 1

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