Help With Structures

Hello I wrote this code but it's not working. I would be very greatful if anyone could help me out. It passes the structure as a function parameter into another function and returens it's values for the desired variable. I will be very graet full if anyone could help me and point out the mistakes.

Code:

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#include <stdio.h>

float test(information_t in);

typedef struct{
        int number;
        int place;
        int postcode;
} information_t;

int main()
{
        information_t information;
        information *in;
       
printf(" Please enter the number: ");
scanf(" %d",&information.number);

printf(" Please enter the place: ");
scanf(" %d",&information.place);

printf(" please enter the postcode: ");
scanf(" %d",&information.postcode);

test(information_t in);

return 0;
}

float (information_t in)
{
        char position;
        position= scanf(" %d%d%d", in->number, in->place, in->postcode);
       
return(position);
}

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Few things:

1. You use information_t before declaring it, in your function prototype for test.
2. When you define the test function, you haven't given it a name, you have float (information_t in) instead of float test (information_t in)
3. When you call the test function, you are passing the type, when you shouldn't be, just pass the parameter.
4. I think your intention was to pass a pointer to the information_t struct, not the value, so you need float test (information_t *in) and call with test(&in);
5. The scanf's in main are correctly done with an & to get the address of the field, but the scanf in the test function has just in->number, when it should be &in->number
6. Your function is declared to return a value, but you do nothing with the returned value.
7. scanf returns an int, but you pass a char.
8. Your function returns a float, but you are returning an integer type.

Thanks cwr for your advice it really did help clear up a few things.

But I just don'nt know how to pass the parameter to the gunction test. I want to pass the sturcture as a function parameter and uses it's variables in the new function. I was hoping If somebady can show me how to do it.

Code:

---


#include <stdio.h>

typedef struct{
        int number;
        int place;
        int postcode;
} information_t;

int test(information_t *in);

int main()
{
        information_t information;
        information *in;
       
printf(" Please enter the number: ");
scanf(" %d",&information.number);

printf(" Please enter the place: ");
scanf(" %d",&information.place);

printf(" please enter the postcode: ");
scanf(" %d",&information.postcode);

test(&information_t  *in);

return 0;
}

int test(information_t  *in)
{
        int position;
        position= scanf(" %d%d%d", &in->number, &in->place, &in->postcode);
       
return(position);
}

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Quote:

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Originally Posted by HAssan

Code:

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        information_t information;
        information *in;

---

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what do you think this section of code is doing? information is a variable of type struct. You cannot create a pointer to a variable in this manner. You could, however do something like this:

Code:

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information_t information;
information_t * in = &information;

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which will create a pointer to the variable information of type "information_t". I think this is what you are trying to accomplish (just guessing though).

Quote:

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Code:

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test(&information_t  *in);

---

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ABSOLUTELY WRONG.
Your function test takes a variable of type pointer-to-information_t. You are passing it the address of a structure (which i'm not sure if this even exists) and then a dereference of a pointer-to-(variable of type information_t), which is of course not valid at all.

You need to have something like this

Code:

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some_int_variable = test(in);

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or more simply without the pointer declaration earlier

Code:

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some_int_variable = test(&information);

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which of course assumes that some_int_variable is declared earlier as an int.

Which leads me to my next point: Why does your test function return an int? It serves no purpose. Why not just use void return type?

Quote:

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Code:

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        information_t information;
        information *in;

---

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"information" does not name a type. That won't work at all.

Code:

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information_t* in;

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By the way, that creates a "wild" pointer, one's that's not pointing to anything. Either give it some memory with malloc() or assign it to 0 or NULL.