CODEWITHSUNDEEP
cstructupdating
John
John

Reputation: 9

How to properly update this field in struct in C

trying to remember the syntax for updating a pointer in a struct. I have something like this for example.

typedef struct {
    char *name;
}car;

And I have a function which is called

void update_Name(car *d, char *newname)
{
    car->name = &newname;
}

Is that correct or would it just be simply newname? Very straight forward dont worry about any other syntaxes or functions needed just wanted to know straight up how that would be updated. Thank you

Upvotes: 0

Views: 899

Answers (2)

dbush
dbush

Reputation: 224457

First, car->name is not correct because car is the name of a type, not a variable. You want d->name instead.

With that correction, the type of d->name is char *. You're attempting to assign an expression of type char ** to it which doesn't match.

newname is already of type char * which matches the type of d->name, so you can assign it directly.

d->name = newname;

Upvotes: 0

Zan Lynx
Zan Lynx

Reputation: 54355

That is not quite correct.

You have a char *newname function parameters. You have a char *name struct member. &newname creates a pointer to newname which would be char **. Not what you want.

You just want car->name = newname; That assigns a char* to a char*.

Always be sure to compile your programs with maximum warning levels. It will tell you when you assign mismatched pointers.

And also in code like this remember memory and pointer lifetimes. You are assigning a pointer to characters into a structure. Whatever that points to needs to survive at least as long as your car structure or your car->name will become a "dangling pointer" pointing to dead memory.

Upvotes: 2

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