Structures and floats

I'm using an UNIX os, the schools, and I'm having trouble literally assigning a value to a structure variable.

Here's the simple code...

#include <stdio.h>

structure example
{
float gpa;
};

typedef struct example Example;

Example number;

int main()
{
number->gpa = 5.65;
return 0;
}

It complies, but when I run it, I get Segmentation fault (core dumped)..

Why does this happen? Please help.

Josh

Use the dot operator rather than the arrow ->

Code:

---

number.gpa = 5.65;

---

The arrow is a shorthand way to derference an object. You did not define a pointer to the structure so you do not require using the arrow.

Since the structure only has one variable (float gpa) why not just do something like this:

Code:

---

typedef unsigned float GPA; /* its unsigned since a gba isn't negative*/
GPA grades = 0.01;

---

Firstly, I think that except for C++, you must use the "struct" keyword to declare a new one of a certain type. Also you may omit one layer of that declaration:

typedef struct example
{
float gpa;
};

struct example number;

Second you are using pointer notation to access a struct, not a pointer to a struct.

printf("/"number/" GPA data is %.2f...\n", number.gpa);

Good Luck!

Oops... I made a typo in my initial code...

it was supposed to be Example* example.

That's why I'm so bothered... because it crashes on a very simple application.

Josh

remembe a pointer points to memory.

try this

int main()
{
Example ex;
number = ex;
number->gpa = var;
return 0;
}

> it was supposed to be Example* example.
Whenever you have a pointer variable, it is YOUR responsibility to make sure it points somewhere. Judging from your initial post, this will be a global variable, and thus be initialised to the NULL pointer (this pretty much guarantees a segfault on *ix operating systems).

&nbsp; Example *number; // your uninitialised pointer
....
&nbsp; Example foo;
&nbsp; number = &foo; // point at variable of the same type
or
&nbsp; number = malloc( sizeof(Example) ); // dynamically allocate

Then you can do number->gpa stuff without problems.