Structs and pointers

[PrOfUnD Darkness]

I have a pointer to a struct like this:

struct list_type *vmuq;

I can manipulate this struct without any problem, but when I pass it to a function like this:

salva_questoes_vmu(vmuq);

looks like it don't pass anything at all, I can't access any value of it from inside the function:

void salva_questoes_vmu(struct list_type *tmpvmuq) {
...
bla bla bla
...

printf("%s\n", tmpvmuq->right);

the printf above just prints nothing...


Any idea?

[q_006]

coluld you show the code for that function?

it'll better help others (such as myself) who would like to help you.

[PrOfUnD Darkness]

There's nothing special on it. It just use the KOS vmu functions to create a package. Even if the first line of the function is the printf shown above, it doesn't print anything.



PD

[Vorrtexx]

are you allocating memory for the structure pointer?

Code: Select all

	list_type *vmuq = (list_type *)malloc(sizeof(list_type));

	strcpy(vmuq->right,"blah blah");
	salva_questoes_vmu(vmuq);



	void salva_questoes_vmu(list_type *tmpvmuq) { 
		printf("%s\n", tmpvmuq->right);
	}

[PrOfUnD Darkness]

Yes, I'm.

Code: Select all

strcpy(vmuq.right,"blah blah");
printf("%s\n", vmuq.right);
salva_questoes_vmu(vmuq);

void salva_questoes_vmu(list_type *tmpvmuq) {
printf("%s\n", tmpvmuq->right);
}

On the code above, the first printf works, the second one don't

[GPF]

somehow you have to pass the address of where the struct begins.

Code: Select all

struct list_type *vmuq, z;

z=&vmuq;

salva_questoes_vmu(z);

or just

Code: Select all

salva_questoes_vmu(&vmuq);

It been awhile so I could be wrong on the syntax.

Troy

[Vorrtexx]

Yes, I'm.

Code: Select all

strcpy(vmuq.right,"blah blah");
printf("%s\n", vmuq.right);
salva_questoes_vmu(vmuq);

void salva_questoes_vmu(list_type *tmpvmuq) {
printf("%s\n", tmpvmuq->right);
}

On the code above, the first printf works, the second one don't

Well from the code you presented, it doesn't look like you declared vmuq as a pointer, because you are accessing vmuq wit the "." in the first and 2nd lines rather than "->"

Then you're passing the variable to a function that required the address of the variable. So you might want to replace your third line with salva_questoes_vmu(&vmuq).

if vmuq has been declared as a pointer, then you can call it like so:
salva_questoes_vmu(vmuq)