CODEWITHSUNDEEP
cstruct
Johnie78
Johnie78

Reputation: 27

C programming how to print out structure's elements when its in another header file?

So I have a struct in another header file

struct MyStackStruct{
    void **stk;
    void *el;
    int sizeStk;
    int top;
    int choice;
};

typedef struct MyStackStruct MyStack;

I call it s in main.

It's fine if I do something like s->top = -1; on another file.c and I can print it out simply by printf("%d", s->top)

But I can't find a solution on how to print out the same thing in main. Nothing I tried works. Help!

Edit1: To make it clear. In struct.h I have

struct MyStackStruct{
    void **stk;
    void *el;
    int sizeStk;
    int top;
    int choice;
};

typedef struct MyStackStruct MyStack;

then in main.c I define it as MyStack* s; and send it to another file with functions using 

MyStack *sP = &s;

and then something like push(sP);

if in push or any other function I do something like s->top = -1; and printf("%d", s->top) it prints out -1. If i do the same printf in main.c it prints out random numbers.

Upvotes: 1

Views: 1112

Answers (1)

fluter
fluter

Reputation: 13786

You can put the struct definition in a header file struct.h, and include it in main.c with #include "struct.h". This way the compiler will have the details of the struct when compiling main.c.

MyStack* s; defines s as a pointer to MyStack, so &s is if type pointer to pointer of MyStack, which is MyStack**. In that case you should just use s for the operation, like push(s).

Also, you need to initialize the pointer before use it, you can use malloc:

s = malloc(sizeof(*s));

Upvotes: 1

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