structures

**mlsbbe** · 03-08-2003

Hello, I am a newbie to C programming, so forgive me if the questions I ask sound stupid.
I am trying to create a program to calculate complex numbers using structures.
I want to pass the value of the structure into the function and let the user change the value of the numbers. However, I keep getting this message:
The left hand argument of '.' must be a structure not '<ptr>complex'.
I have looked at some reference books, but i am still stumped on how to change the value of the structure in the function. Below is the code

<code>
#include <stdio.h>

typedef struct complex{
int real;
int imaginary;
};

void take_values(complex *A);

int main(void)
{
complex A;
take_values(&A);
printf("You have typed %d + j%d ", A.real,A.imaginary);

return(0);
}

void take_values(complex *A)
{

printf("Please enter the real part of complex number, A: ");
scanf("%d", A.real);
printf("Please enter the imaginary part of complex number, B: ");
scanf("%d",A.imaginary);

}
</code>

**Vber** · 03-08-2003

Code:

scanf("%d", A.real);

Should be:

Code:

scanf("%d",A->real);

Or

Code:

scanf("%d",(*A).real);

**Hammer** · 03-08-2003

You've also written the structure typedef incorrectly. It should be

Code:

typedef struct complex 
{
  int real;
  int imaginary;
} complex;

And code tags are done with [] brackets.

**Vber** · 03-08-2003

typedef struct complex
{
int real;
int imaginary;
} complex;

Now I dont understand Hammer

In my book it shows something like this

Code:

typedef struct {
   int real;
   int imaginary;
} complex;

Bahh lame book?

**Hammer** · 03-08-2003

There are various ways you can write it, but this isn't one AFAIK (from the OP)

Code:

typedef struct complex{
  int real;
  int imaginary;
};

Your example is fine.

**Magos** · 03-08-2003

Code:

typedef struct NAME1
{
   ...
}NAME2;

NAME1 is the name of the structure. If you want to create an object of it, you have to use the keyword struct in front:

struct NAME1 MyStruct;

NAME2 is the name of the typed definition that you make using typedef. Using typedefs creates a 'new datatype', so to make an object of it you just have to specify NAME2 instead of struct NAME1:

NAME2 MyStruct;

**v@grant** · 03-10-2003

Hello....i'm just a newbie here.....
could annyone please...tell me if data struct in c is LIFO(last in first out) then the last value/variable that i have input should be the first one to be printed out? and how do I make a temporary memory location for the whole data struct / struct of arrays if i am gonna sort it? should i use/declare a temporary variable in the main() function || declare another data struct with the same as the one i have made....

**Hammer** · 03-10-2003

>>data struct in c is LIFO(last in first out)
Neither. A struct is simply a number of variables grouped together. You access each element of the struct independantly.

If you're talking about an array of structs, its the same principle. LIFO and FIFO are terms normally used for stacks and queues.

>>how do I make a temporary memory location for the whole data struct / struct of arrays if i am gonna sort it?
If you have an array you want to sort, lookup the qsort() function.

**v@grant** · 03-11-2003

Ohh.. I see Thanx.... :-)

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