Thread: Sort my file

Hi

Can someone tell me how can i sort my file created?

The file writed comes from a struct

The fields are char name , float total, int result

My file is printed like this

Name %% result


I want to sort from result the highest to the lower


Any help??

Thanks

Thanks

But i need to read the file into an array, right?

file xx
int array[200]

array=(fread.....


is like this?

FFS you ask so many mundane questions seemingly without trying to solve the problem/researching/reading other answers first. Just look what a basic google search about quicksort will tell you.

Hi

Already did some progress but the data comes unsorted

Code:

int comparador(const void * elem1, const void * elem2)
{
    return ((struct jogoJogado *)elem1)->res_final = ((struct jogoJogado *)elem2)->res_final;
}


int comp()
{
    struct jogoJogado *listas[10];
    FILE *f;
    f=fopen("jogos.dat", "rb");
    if(!f)
    {
        printf("Erro");
    }
    else
    {
      listas[0] = (struct jogoJogado*)malloc(sizeof(struct jogoJogado));
      int i;
      int retorno=fread(listas[0], sizeof(struct jogoJogado), 1, f);
      for(i=1;retorno==1;i++)
      {
          listas[i]=(struct jogoJogado*)malloc(sizeof(struct jogoJogado));
          retorno= fread(listas[i], sizeof(struct jogoJogado), 1, f);


        }
    }
    qsort(listas, 4, sizeof(struct jogoJogado), comparador);
    int i;
    for(i=0; i<4; i++)
    {
        printf("%s   %d    %.2f   \n", listas[i]->nome, listas[i]->res_final, listas[i]->p_certas );
    }
    Sleep(4000);
return 0;
}

Whats wrong??

man qsort:

[...] The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second. If two members compare as equal, their order in the sorted array is undefined. [...]

What does your comparison function return?

Bye, Andreas

Code:

return ((struct jogoJogado *)elem1)->res_final = ((struct jogoJogado *)elem2)->res_final;

This doesn't do what you think it does.

Code:

      listas[0] = (struct jogoJogado*)malloc(sizeof(struct jogoJogado));
      int i;
      int retorno=fread(listas[0], sizeof(struct jogoJogado), 1, f);
      for(i=1;retorno==1;i++)
      {
          listas[i]=(struct jogoJogado*)malloc(sizeof(struct jogoJogado));
          retorno= fread(listas[i], sizeof(struct jogoJogado), 1, f);
 
 
        }

This bit of code will always allocate one more structure than what you read in, and "i" will be one too high. It can also be shortened and simplified (which usually translates to clarity and ease of understanding what it does).

Code:

    qsort(listas, 4, sizeof(struct jogoJogado), comparador);

Where did 4 come from?

Originally Posted by christop

Code:

return ((struct jogoJogado *)elem1)->res_final = ((struct jogoJogado *)elem2)->res_final;

This doesn't do what you think it does.

That was wrong, i didn't see it was - and not =

Code:

      listas[0] = (struct jogoJogado*)malloc(sizeof(struct jogoJogado));
      int i;
      int retorno=fread(listas[0], sizeof(struct jogoJogado), 1, f);
      for(i=1;retorno==1;i++)
      {
          listas[i]=(struct jogoJogado*)malloc(sizeof(struct jogoJogado));
          retorno= fread(listas[i], sizeof(struct jogoJogado), 1, f);
 
 
        }

This bit of code will always allocate one more structure than what you read in, and "i" will be one too high. It can also be shortened and simplified (which usually translates to clarity and ease of understanding what it does).

I believe it can be more simple than that, someone, check some posts above to (google)

Code:

    qsort(listas, 4, sizeof(struct jogoJogado), comparador);

Where did 4 come from?

4 are the numbers i want to sort.

To Andreas:

the print is the following:

4 Top de jogadores
*================================================= ============================*

Before qsort
Gil 10 80.00
Baby 9 87.00
Kill 3 14.00
cerdo 6 87.00


after qsort
Baby 9 87.00
Gil 10 80.00
cerdo 6 87.00
Kill 3 14.00

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My question was not about the outcome of the sorting.
I asked you what does your comparison function return (or better what do you think it returns)?
And how does this fulfill the requirements qsort() demands?

Bye, Andreas

Originally Posted by AndiPersti

My question was not about the outcome of the sorting.
I asked you what does your comparison function return (or better what do you think it returns)?
And how does this fulfill the requirements qsort() demands?

Bye, Andreas

The sorting algorithm used by this function compares pairs of values by calling the specified comparator function with two pointers to elements of the array.

The function does not return any value, but modifies the content of the array pointed by base reordering its elements to the newly sorted order.


qsort - C++ Reference

Iv'e been reading, i don't ask anything before google it...

Originally Posted by AndiPersti

Then you should continue reading page:

That's the part explaining why your compare function doesn't work.

And if you still read further you even get an example of how it works :-)

Bye, Andreas

Hi Andreas, now it works.

With the qsort.


Many thanks

regards