CODEWITHSUNDEEP
cobjectvariablesstruct
rama
rama

Reputation: 53

what is "struct <name_1> <name_2>" in c?

there is a line in c code:

struct name_1 name2;

what this line implies?

my understanding about above line is name_1 is the name of the structure and name2 is the object variable. However name_1 should have been defined somewhere, but I could not find the definition of name_1.

so my question is; is there anything like this where we can have an object of a structure which is not defined anywhere.

Upvotes: 0

Views: 204

Answers (2)

Shaun Jose
Shaun Jose

Reputation: 66

Is there a header file (name.h) you have included in your c code? Usually, structure, constant and function declarations are in the header file, which is 'included' (at the top of your c file), and you could then use those structures and constants in your c file without defining them

Upvotes: 0

M.M
M.M

Reputation: 141648

At file scope, this is the definition of a variable called name2 whose type is struct name_1. If there has not been a previous declaration of struct name_1; then this line also declares that type.

Being a file scope variable definition with no initializer nor storage class specifier, this is a tentative definition. Tentative definitions may have incomplete type so long as the type is completed by the end of the file, e.g.:

#include <stdio.h>

struct foo bar;

void f();

int main()
{
    printf("%p\n", (void *)&bar);
    f();

    // cannot do this
    // printf("%d\n", bar.x);
}

struct foo { int x; };

void f()
{
    bar.x = 5;
}

This sort of code would be uncommon however. If you see struct foo bar; in real code it is more likely that struct foo was previously defined somewhere that you are overlooking.

Upvotes: 2

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