Accessing struct variables outside of function in C

Question

I am having trouble understanding the scope of variables within a struct. For example:

struct Class 
{
const char *name;
int Hitdice, Str_Dice, Dex_Dice, Con_Dice, Int_dice, Wis_Dice, Cha_Dice, Skill_Points, level;
double BAB_Type;
struct Class *next_Class;
};

void setName()
{
struct Class setName;
setName.name = "thomas";
}

int main()
{

}

Is the variable *name only set to "thomas" within void setName()? How would I make it so that if I give a value to a struct variable that that value is accessible globally. If I was to print out the variable name within int main() it would be blank, how would I make it print out "thomas"? Or is that only doable within the function setName()?

The struct is the same as any other local variable. You can't access local variables to a function from outside the function. — jamesdlin
– jamesdlin, Commented Oct 29, 2014 at 19:35
You will have to malloc the memory for "thomas" if you want your global struct to still point to it. I suggest returning the char* from the function in order to be able to free it later. — LeatherFace
– LeatherFace, Commented Oct 29, 2014 at 19:35
If you tried to print it out within main(), you'd get a compiler error, since the setName variable is only declared within the setName() function. It's not that setName.name is "unset" when the function exits, it's that the setName struct doesn't exist outside the function in which it's declared. — Paul Roub
– Paul Roub, Commented Oct 29, 2014 at 19:36
@LeatherFace What "global struct" do you see in the example? — Paul Roub
– Paul Roub, Commented Oct 29, 2014 at 19:36
He will have to declare a global structure then delete the local structure in the function. — LeatherFace
– LeatherFace, Commented Oct 29, 2014 at 19:37

Sergey Kalinichenko · Accepted Answer · 2014-10-29 19:37:46Z

4

Is the variable name only set to "thomas" within void setName()?

Yes. That's the essence of how local variables work

How would I make it so that if I give a value to a struct variable that that value is accessible globally?

Make struct Class setName; global by declaring it outside setName function. I suggest also giving it a different name - say, theClass.

You should also change setName to take both the name and struct Class on which you would like to set the name.

If I was to print out the variable name within int main() it would be blank, how would I make it print out "thomas"?

Once you move the declaration outside setName() function, you would be able to access it from anywhere you'd like.

struct Class {
    const char *name;
    int Hitdice, Str_Dice, Dex_Dice, Con_Dice, Int_dice, Wis_Dice, Cha_Dice, Skill_Points, level;
    double BAB_Type;
    struct Class *next_Class;
} theClass;

void setName(struct Class *myClass, const char* theName) {
    myClass->name = theName;
}

int main() {
    setName(&theClass, "thomas");
    printf("%s\n", theClass.name);
    return 0;
}

answered Oct 29, 2014 at 19:37

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Emmett Over a year ago

Thank you, perfect explanation. 10/10.

Collectives™ on Stack Overflow

Accessing struct variables outside of function in C

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related