Thread: write structe to a file and then randomize func

wow, gonna need some work.

Does *p point to an array?
You should probably also pass the max elements of the array as well.
You could also use p[xxx].

Next, you read in one chunk the size of perg to the pointer.
Then you go into a loop that reads lines.
Don't you want to continue to read chunks -o- perg into the array?

There is more wrong.
Start over and write a pseudocode outline which includes a workable calling function.

Originally Posted by Gil Carvalho

Code:

    if ((f = fopen("Atividades/gp1.dat", "wb")) == NULL)

You won't read anything from that file because opening it for write truncates the file. You'll want to use "rb" to open it for reading.

Hi

Code:

char lista[1000][256];
.....
while (fgets(lista[i], 256, f) == lista[i])

The erro comes in the while

Warning comes with the char

Howard, thanks again


My steps:

create a variable to read how many records are in the file
create an array
Read file into the array
count the records

call (random) to choose x records

regards

If the structs in the file are stored in binary your fgets(lista[i], 256, f) == lista[i] idea may not work out so well.
But forget that for now. Work on your pseudo code.

Code:

create a variable to read how many records are in the file
create an array
Read file into the array
count the records
call (random) to choose x records

Ok so put those in function blocks where they will be declared and occur. ie: main(), F1(), F2() ...
INDENT your code

Originally Posted by HowardL

If the structs in the file are stored in binary your fgets(lista[i], 256, f) == lista[i] idea may not work out so well.
But forget that for now. Work on your pseudo code.

Code:

create a variable to read how many records are in the file
create an array
Read file into the array
count the records
call (random) to choose x records

Ok so put those in function blocks where they will be declared and occur. ie: main(), F1(), F2() ...
INDENT your code

pseudocode:

Code:

Variables
cont, rand, i
char lista[1000][256];
open file
cont = 0
while (fgets lista == struct *p)
cont++
I know how many (cont)
close file
rand = random()%count

is that??

Howard, and how about dinamic memeory allocation?? Do you think it's easier or not?

Many thanks

Thanks Howard, i'm learnig that language and sometimes i think something can be the way i think and is not, i have modified my code to:

Code:

void jg2(struct perg *p)
{

    char * lista[1000][256]; // mil perguntas com tamanho máximo de 255 caracteres
    int count;
    FILE *f;
    if ((f = fopen("Atividades/gp1.dat", "rb")) == NULL)
    {
        printf("Erro ao abrir ficheiro\n");
    }
    else
    {
        count = 0;
        while (fgets(lista[count], 256, f) == lista[count])
        count++;
        // fechar ficheiro
        fclose(f);
        //escolher pergunta
        rand() % count;
    }
}

I have no errors now but two warnings

(while)
comparison of distinct pointer types lacks a cast [enabled by default]
passing argument 1 of ‘fgets’ from incompatible pointer type

I'm creating variables,
array
open my file
put the variable count to 0
get the contents of my file to lista
closing the file
random the count

Still ridiculous? Hope no....i'm struggle to do better thanks to you