error: request for member 'valore' in something not a structure or union

Question

It tells me that there was an error. For me it's a problem of pointer or something about the structure, but I don't know exactly.

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

typedef struct
{
    char luogo[20];
    float valore;
}rilevazione;

void BubbleSort(float valore[], int n);

int main()
{
int i=0, n=0, j=0;
rilevazione*dato=NULL;

dato=(rilevazione*)malloc(MAX*sizeof(rilevazione));

while(i<MAX)
{
    printf("inserisci luogo %d: ", i+1);
    scanf("%s", dato[i].luogo);
    printf("inserisci valore %d: ", i+1);
    scanf("%f", &dato[i].valore);

    if(strcmp(dato[i].luogo, "end")==0) break;
    i++;
}

n=i;
printf("il numero di misure e' %d", n);
scanf("%d", &n);

BubbleSort(dato.valore, n);
for(j=0; j<n; j++)
{
    printf("valore: %d  luogo: %s", dato[i].valore, dato[i].luogo);
}





return 0;
}

void BubbleSort(float valore[], int n)
{
int i=0, temp=0, j=0;
int scambi=1;

while(i<=n && scambi!=0)
{
  scambi=0;
  j=n;
  while(j>=i)
  {
      if(valore[j]>valore[j+1])
      {
          temp=valore[j];
          valore[j]=valore[j+1];
          valore[j+1]=temp;
          scambi=1;
      }

      j=j-1;
  }
 i=i+1;
}
return;
}

Welcome to SO. Your question is not of very good redactional quality. Cook your problem code down to a minimal example. Indent your code such that it is readable. Tell us in which line your error is reported, first. — Jens Gustedt, Dec 11 '13 at 21:12

score 0 · Answer 1 · answered Dec 11 '13 at 19:27

0

Your BubbleSort takes an array of floats but you are are trying to pass it just one float and not correctly either. dato.valore has no meaning. dato[n].valore does. Do you see the difference?

Choices:

create an array of floats from your array of structs.
Update BubbleSort to sort the struct array you already have.
Update your sort routine to take a function pointer and calls the function for each item in the list to be sorted.

The last choice is how most libraries deal with this.

answered Dec 11 '13 at 19:27

Sean Perry

3,776
1
19
31

@user3092558, pick a choice from my list and post some updated code. – Sean Perry Dec 11 '13 at 20:15
i change but it's the same problem BubbleSort(dato[i].valore, n); – user3092558 Dec 11 '13 at 20:18
@user3092558, dato[i].valore means the i-th item in the array's data member valore. Do you see how asking to sort one entry will not work? You are doing the equivalent of `BubbleSort(3.14, n);` – Sean Perry Dec 11 '13 at 20:20
Welcome to programming @user3092558. It can be overwhelming at times. The trick is to come up with small steps that lead to victory. Ask yourself, if this code was working 100% what should `BubbleSort` take as input and return as output. Ok, what is the step right before working where `BubbleSort` is almost working but your are missing one piece? Keep walking backwards and eventually you will end up at the right place. – Sean Perry Dec 11 '13 at 20:27
bubbleSort take as input the struct...and as output it takes me an error....i don't understand if the problem is in void BubbleSort(float valore[], int n) or in BubbleSort(dato.valore, n); – user3092558 Dec 11 '13 at 20:30

score 0 · Answer 2 · answered Dec 11 '13 at 19:27

0

That's probably because when you do BubbleSort(dato.valore, n); you are missing an index in dato... which is a pointer.

So you would need something like dato[XXX].valore.

answered Dec 11 '13 at 19:27

luis

11
1

score 0 · Answer 3 · answered Dec 11 '13 at 19:28

rilevazione*dato=NULL;

dato=(rilevazione*)malloc(MAX*sizeof(rilevazione));

change to

rilevazione *dato;

dato=(rilevazione*)malloc(MAX*sizeof(rilevazione));
if (dato == NULL) { error in malloc'ing data array...

Always check the result of a memory allocation. I'm not sure if C will recognize a pointer declaration when it's all jammed together -- better be safe and put a space in there.

Since dato is an array (actually, a pointer to an array), I suspect that your call to BubbleSort() is not happy with treating it as a scalar structure. You're going to have to pass the entire array of structures into BubbleSort and pick apart the valore component inside the function.

I'll assume that the use of a Bubble Sort is merely incidental and that for real production code you'd use something a little faster running.

also please remove the cast before the call to `malloc`. this is C and not C++. — Jens Gustedt, Dec 11 '13 at 21:14
no, no, no, as I said this is C and not C++: http://stackoverflow.com/questions/605845/do-i-cast-the-result-of-malloc — Jens Gustedt, Dec 11 '13 at 22:57

score 0 · Answer 4 · answered Dec 11 '13 at 19:31

0

That's probably because when you do BubbleSort(dato.valore, n); you are missing an index in dato... which is a pointer, so it needs an index.

So you would need something like dato[index].valore.

answered Dec 11 '13 at 19:31

luis

11
1

Sorry, I wanted to edit, but mistakenly put a new answer. [new stackoverflow user...] – luis Dec 11 '13 at 19:32
No, putting an index in it would simply pass one structure or one element of one structure, which makes no sense to sort. You need to pass the entire array to a sorting function, and handle the complexity of each element being a structure and not a scalar. – Phil Perry Dec 11 '13 at 21:27

error: request for member 'valore' in something not a structure or union

4 Answers4