Thread: Linked Lists please help!!!

fwrite() writes bytes to the file.

So if you have for example an int value 10 and your system uses 4 bytes for an int, then on a little endian system the value is stored as 0a 00 00 00 and on a big endian system it is stored as 00 00 00 0a. fwrite() will write these 4 bytes to the file.

If you open the file in a text editor, the editor interprets these bytes as characters (in ASCII one byte/character). That's why you get strange symbols.

You should write the numbers to your text file with fprintf().

Bye, Andreas

I change the line with fprintf() but nothing... I actually did this :

Code:

   .......
   .......
   srand( time(NULL) );

    for ( i = 0 ; i < N ; i++ )
    {
        random_number = rand()%LIMIT;
        fprintf( fp, "%s\n", &random_number); //This is the line i have changed
        printf ( "%d\t", random_number) ;
    }
    fclose(fp);

Please, i appreciate if you tell me how i should change that line to make my program work fine.

Thank you.

I don't understand i should use fprintf() or not...??? And if is ok the way i have changed it why it still doesn't print the numbers in the input.txt???

Ok thank you for your help. I have fixed it. It seems that the problem was in main something.

Hello again. I have an issue in a program i made. Actually i made this: I created a file and i stored into it, an array of random numbers. First i have to tell the user to give how many numbers wants to put into the array and let's say he says 5 the first number of the array will be 5. So i did it but i have managed to do all code in main, so i want know to create functions and call them in main when i need them. My problem is that i have tried to create the functions but i can not make them work properly. Can anyone help me and tell me how i am supposed to do the functions?

This is the hole code without the functions i have done so far:

Code:

# include <stdio.h>
# include <conio.h>
# include <stdlib.h>
# include <time.h>

# define LIMIT 1000

int main()
{
    FILE *fp ;
    char str[67] ;//This is an Array of ch where we store the name of the file
    int i, N, random_number;
    int Array[N]; //Create an Array[] of size N

    //clrscr() ;

    printf ( "Please give the name of the file: " ) ;
    scanf ( "%s", str ) ;

    printf ( "Please give the element of numbers in the array you want: " ) ;
    scanf ( "%d", &N ) ;
    printf("\n");

    fp = fopen ( str, "wb" ) ;
    if ( fp == NULL )
    {
        printf ( "The file can not be created." ) ;
        getch() ;
        exit (0) ;
    }

    srand ( time(NULL) );

    Array[0] = N;
    fprintf(fp, "%d \n", Array[0]);
    printf("%d\t", Array[0]);

    for ( i = 1; i < N; i++ )
    {
        Array[i] = rand()%LIMIT;
        fprintf(fp, "%d \n\n ",Array[i]);
        printf( "%d\t", Array[i]) ;
    }

    fclose (fp) ;
    printf("\n");
    printf ( "\nThe file has been created." ) ;

return 0;
system("pause");
}

Thank you in advance!!

Code:

int i, N, random_number;
int Array[N]; //Create an Array[] of size N

That doesn't work. "N" is used uninitialized so it contains garbage. You can't declare the array before you read a value for "N".

Code:

fp = fopen ( str, "wb" ) ;

You write the numbers as text, thus you shouldn't open the file in binary mode.

Originally Posted by ValL

My problem is that i have tried to create the functions but i can not make them work properly. Can anyone help me and tell me how i am supposed to do the functions?

Have you read already about functions in C?

What functions do you want to create? What problems do you have (show us your attempts)?

Bye, Andreas

Originally Posted by ValL

Actually the exercise says to create a program where you create a file and store into it an array of integer random numbers with first number the N (length of the array the user wants) for example if he wants 5 elements in the array the first number of the array will be 5 and the other 4 the random numbers are created.

Then it says to sort the array with the heap sort and put the sorted array in another file. I sent you that program i have tried because i am trying to do it piece by piece see that it works and then continue with the other pieces of the program. I have read about the files but i can't understand the way i have to copy the array from one file to the other. I will appreciate it a lot if you explain me how i can make this step. And after that i will try the other steps us well!!!

Ok, you have to write an integer array to a file twice.

So for a start I suggest writing a function (e.g. "write_array") which takes three parameters (a file pointer, an array of ints, the size of the array) and write the contents of the array to the given file. You have already written code for this task. Are you able to extract these code lines and put them into the function?

Bye, Andreas

Yes, ok thank you so much for your help i will try to do it like you said and i will tell you if is working.