a C structure problem
hi
i need two structure which is basically like this
i get a error : LINE :8 ISO C++ forbids Declaration Of 'Alphabet' With No TypeCode:struct Symbol { Symbol * E; Alphabet * N; //line 8 }; typedef struct Alphabet { char data ; Symbol * E; };
so i guess alphabet type is not defined yet i mean at that point, how do i overcome this problem
Add
struct Alphabet;
before Symbol.
Originally Posted by Adak
i think that will create similar problem as symbol is not defined at that point, correct me if i am wrong
Symbol exists; it's a struct, and a struct being defined can refer to itself, although within limitations. So no problems.
thanks for you quick reply
but its not working for me
i am using DEV C++ With GCC CompilerCode:typedef struct Alphabet { char data ; Symbol * E; //shows error: ISO C++ forbids Declaration Of 'Symbol' With No Type }; struct Symbol { Symbol * E; Alphabet * N; //line 8 };
Code:struct Alphabet; struct Symbol { Symbol * E; Alphabet * N; //line 8 }; struct Alphabet { char data ; Symbol * E; };
ok thanks i get it, (i didn't know that structure can be declared in that way)
Last edited by bioshock; 02-28-2011 at 01:45 PM.
It's called a forward declaration. It tells the compiler "hey there is this struct called Alphabet but you don't need to know the details just yet." It allows the compiler to parse through that Symbol struct without causing issues like you are getting because now the compiler knows in general what it is (a struct) even if it does not know exactly what it looks like in detail.
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thanks hk_mp5kpdw for the explanation
