Thread: reading from bin file

didn't you have this thing working or almost working. that code is looking rather familiar now that I read some of it. there was a entire post on this where whiteflags and I got into a discussion on this. here is that very very similar code that is working code.

Code:

#include <stdio.h> 
#include <ctype.h> 
#include <string.h> 
#include <math.h> 
  
  
#define N 100  // number of points 
#define TRUE 1 
#define FALSE 0 
#define EPSILON 1e-10 
#define BINFILE "file.bin" 
 
typedef struct LITTEINFO 
{ 
  
   double l; // starting time 
   double c; // ending time 
   double v; // velocity 
   double td; // time 
   double pc; // altitude 
  
  
} INFO; 
  
  
int main() 
{ 
    int i=0; 
    int flag = FALSE; 
    int ans; 
    INFO data2[10];  
    FILE *fp2; 
      
     if (( fp2 = fopen(BINFILE, "wb+")) == NULL) 
     { 
         printf("no file yet\n"); 
            fp2 = fopen(BINFILE, "wb+"); 
    } 
            
    while(i < 10 && flag==FALSE) 
    { 
        printf("Please enter the value for L:\n"); 
            scanf("%lf",&data2[i].l); 
        printf("Please enter the value for C:\n"); 
            scanf("%lf",&data2[i].c); 
        printf("Please enter the value for the battery voltage:\n"); 
            scanf("%lf",&data2[i].v); 
        printf("Please enter the value for the dissipation time td:\n "); 
            scanf("%lf",&data2[i].td); 
        printf("Please enter the value for the percentage of the\n" 
                "original charge pc to reach within td\n"); 
                scanf("%lf",&data2[i].pc); 
    
                          
        fwrite(&data2[i].l, sizeof(double), 1, fp2);  
        fwrite(&data2[i].c, sizeof(double), 1, fp2);  
        fwrite(&data2[i].v, sizeof(double), 1, fp2);  
        fwrite(&data2[i].td, sizeof(double), 1, fp2);  
        fwrite(&data2[i].pc, sizeof(double), 1, fp2);  
         
        //fwrite(&data2, sizeof(data2), 1 ,fp2);      
        i++; 
         
        printf("do you want to \n" 
        "1. enter a new set of values(max 5)\n" 
        "or\n" 
        "2.choose a saved set of values\n"); 
            scanf("%d",&ans); 
             
        if (ans == 2) 
            flag = TRUE; 
    } 
 
    printf("which set of values do you want to see?\n"); 
        scanf("%d",&ans); 
 
    rewind(fp2); 
    // compensate for zero element. 
    if ( ans-1 > i) 
    { 
        printf("out of bounds\n"); 
        return -1; 
    } 
    else 
    { 
        //from stuc 
        printf("\n%.2lf %.2lf %.2lf %.2lf %.2lf", data2[ans-1].l, data2[ans-1].c, data2[ans-1].v, 
        data2[ans-1].td, data2[ans-1].pc); 
         
        printf("\nSKIP LINE\n"); 
        //from file? 
        fread(data2, sizeof(data2), i, fp2); 
            printf("\n%.2lf %.2lf %.2lf %.2lf %.2lf", data2[ans-1].l, data2[ans-1].c, data2[ans-1].v, 
        data2[ans-1].td, data2[ans-1].pc); 
    } 
     
    // trying to get where to start, and how many lines. 
    // no check for over shoot array yet.  
    // and whatever other little tweeks that maybe 
    // needed.  
     
      
    fseek(fp2, 0 , SEEK_SET); 
    char ch; 
    int start, amount;  
    size_t whatsInThere; 
    printf("\nWould you like to see more than 1 file? y/n\n"); 
        scanf(" %c",&ch); 
         
    if(tolower(ch) == 'y') 
    {  //clear struct / zero out struct 
        memset(&data2, 0, sizeof(data2)); 
        printf("how many files and starting from which one?\n"); 
        scanf("%d%d", &amount, &start); 
      
     printf("size of : %ld\n", (i*sizeof data2[0])); 
      
      
        whatsInThere = fread(&data2, sizeof(data2), i, fp2); 
        printf("whatsInThere %zu\n", whatsInThere); 
            if (amount <= i ) // if over total added else 
            {  
                // read entire file using i  
                fread(data2, sizeof(data2), i, fp2); 
                int d = 0; // do not go over amount wanted. 
                        for (; d < amount; d++) 
                        { // start where said to start 
                            printf("\n%.2lf %.2lf %.2lf %.2lf %.2lf", data2[start-1].l, data2[start-1].c, data2[start-1].v, 
                            data2[start-1].td, data2[start-1].pc); 
                            start++; // move it down the array elements.  
                              
                        }     
                        printf("\n");                     
                              
            }         
        else 
        { 
            printf(" woo dude not valid, good-bye\n"); 
            fclose(fp2); 
            return -1; 
        } 
    } 
    else 
    { 
        printf("fine c ya\n"); 
    } 
             
    fclose(fp2); 
    remove(BINFILE); // get a clean file each run 
 return 0; 
  
}

is that not (mostly) your code??

you might want to get a look at how it is being printed out, getting the sizes and everything else it is doing, and opening the file with wb+ ( read write binary)

well for one forget about what I said about sizes . my mistake. but your prototypes are wrong, that might have something to do with it

Code:

// Function Prototypes
void findRoot(INFO[], int , double * );
void plotFunc(double, double, int, double []);
double func(INFO [],int , double);
void plot(int,  double[], double[], int, double[], double[]);
double getMin(double *, int );
double getMax(double *, int );

Code:

gcc -Wall -Wextra -Wpedantic -lm -o "read_write_binary_001" "read_write_binary_001.c" (in directory: /home/userx/bin)
read_write_binary_001.c: In function 'findRoot':
read_write_binary_001.c:165:1: error: parameter name omitted
 void findRoot(INFO[], int , double * )
 ^
read_write_binary_001.c:165:1: error: parameter name omitted
read_write_binary_001.c:165:1: error: parameter name omitted
Compilation failed.

I made a dummy function using your prototype to get that for you.

MOD:

regardless writing manipulating your data then writing to it then reading from the same file what you do to it in the middle has nothing to do with how you get it out of the file then print it out.
this is suppose to be passing a value back out of the prams then printing it?

Code:

findRoot(data2,ans,&root);

printf("%lf\n",data2[ans-1].l);

Originally Posted by Kamal Joub

so i made a program , where the input of the user is saved in a binary file , what i want to do tho is use the values saved in the binary after the program is restarted , meaning use previously inputted values.

However , when i test to see if the program read he correct values from the binary file , i keep getting 0. The following is the code related only to this issue please ignore the prototypes thanks.

btw , i am also trying to check if the file exist and contain elements(Hence the != NULL in the beginning of main) to display it to the user but NULL doesn't seem to do the trick since even if the bin file don't exist it prints the statement indicated.So , please if possible help with that too but the first issue is the priority.

what'a ya mean by keep getting 0?

to check for a file

Code:

#include <stdio.h>
#include <math.h>
#include <unistd.h>
 
#define N 100  // number of points
#define TRUE 1
#define FALSE 0
#define EPSILON 1e-30
#define BINFILE "file.bin"
#define pi 3.1415926535897932384626433832795
 
 
typedef struct
{
 
 
   double l; // starting time
   double c; // ending time
   double v; // velocity
   double td; // time
   double pc; // altitude
 
 
} INFO;
 
 
 
int main()
{
 
 
 if( access( BINFILE, F_OK ) != -1 )
 {
    // file exists
    printf("yep its here\n");
}
 else
 {
    // file doesn't exist
    printf("no file exist\n");
    return -1;
}

Code:

userx@slackwhere:~/bin
$ rm file.bin
userx@slackwhere:~/bin
$ ./read_write_binary_001
no file exist

I doubt the prototypes are the problem since what i am printing here as a test is only related tot he main function i am not printing anything from the functions , also i noticed in your 2nd code that all the errors regarding the reading are coming from the other functions not main but the other functions aren't supposed to read anything from bin file , then how am i still getting a wrong value when printing it after restarting the program.Also , yes that findRoot should pass the root value back and printing it is working just fine when before restarting the program , then the wrong values are read from the bin file.

and I mean by getting zero , that after closing the program and opening it again the output of printf is not the value of data2[ans-1].l , i get an output of zero, which i assume is a garbage value and is caused by misreading the bin file

I feel i'm missing something , I mean i wish i could read in .txt the contents of the bin file to see what's stored but if u remember from the other post , we've established that the program writes and reads in and from the bin file correctly so the problem comes after closing it and restarting , how come the values read into it are printed out correctly , i feel it's 1 of 2 possibilites , either I am reading the wrong part of the file(doubtful) or the values are getting erased after closing the program which would weird since i have no Remove(BINFILE) or any such commands in my program.

Originally Posted by userxbw

they are a problem for me, when I try to compile it to run it to see what is really going on well them bad prototypes get in the way. and that last function call looked important. and I have no idea what your functions are doing to get a perspective if they maybe hindering you in some way or not.

as far are you bin file I found that I have to delete mine from time to time because they get corrupted for whatever reason. just for to find out, delete your bin file make a new one with your program and then try it again to see what you see if you have not already tried that.

I have tried deleting the bin file several times , it's not corrutped per say , it's just the values start overlapping so u end up reading the same values over and over. Here is my full code so far , to give you a better perspective

Code:

#include <stdio.h>
#include <math.h>


#define N 100  // number of points
#define TRUE 1
#define FALSE 0
#define EPSILON 1e-30
#define BINFILE "file.bin"
#define pi 3.1415926535897932384626433832795


typedef struct
{


   double l; // starting time
   double c; // ending time
   double v; // velocity
   double td; // time
   double pc; // altitude


} INFO;


// Function Prototypes
void findRoot(INFO[], int , double * );
void plotFunc(double, double, int, double []);
double func(INFO [],int , double);
void plot(int,  double[], double[], int, double[], double[]);
double getMin(double *, int );
double getMax(double *, int );




int main()
{
    int i=0;
    int flag = FALSE;
    int flag2;
    int ans;
    INFO data2[5];
    FILE *fp2;
    double root , R;
    double check , check2;
    double f;
    char ans2;


     if (( fp2 = fopen(BINFILE, "wb")) != NULL )
     {
         printf("Do you want to choose previously inputted values? (y/n)\n");
         fflush(stdin);
         scanf("%c",&ans2);


         if (ans2 == 'y')
            flag = TRUE;


            fp2 = fopen(BINFILE, "wb");
    }


    while(i < 5 && flag==FALSE)
    {
      do
      {
          flag2 = TRUE;
        printf("Please enter the value for L:\n");
            scanf("%lf",&data2[i].l);
        printf("Please enter the value for C:\n");
            scanf("%lf",&data2[i].c);
        printf("Please enter the value for the battery voltage:\n");
            scanf("%lf",&data2[i].v);
        printf("Please enter the value for the dissipation time td:\n ");
            scanf("%lf",&data2[i].td);
        printf("Please enter the value for the percentage of the\n"
                "original charge pc to reach within td\n");
                scanf("%lf",&data2[i].pc);


        R = (-2* data2[i].l * log(data2[i].pc))/data2[i].td;
        check = 1/(data2[i].l*data2[i].c);
        check = check - pow((R/(2*data2[i].l)),2) ;
        check2 = sqrt(check);
        f = check2/(2*pi);
        f= 50/f;


        if(check < 0)
        {
           flag2 = FALSE;
           printf("Invalid input , Please enter a bigger value for td\n");
        }
        if(f < data2[i].td)
        {
            flag2 = FALSE;
            printf("Frequency too high; plot may be distorted\n");
        }




      }while(flag2 == FALSE);




        fwrite(&data2[i].l, sizeof(double), 1, fp2);
        fwrite(&data2[i].c, sizeof(double), 1, fp2);
        fwrite(&data2[i].v, sizeof(double), 1, fp2);
        fwrite(&data2[i].td, sizeof(double), 1, fp2);
        fwrite(&data2[i].pc, sizeof(double), 1, fp2);


        //fwrite(&data2, sizeof(data2), 1 ,fp2);
        i++;


        printf("do you want to \n"
        "1. enter a new set of values(max 5)\n"
        "or\n"
        "2.choose a saved set of values\n");
            scanf("%d",&ans);


        if (ans == 2)
            flag = TRUE;
    }


    printf("which set of values do you want to use?\n");
        scanf("%d",&ans);


    fclose(fp2);


    fp2 = fopen(BINFILE, "rb");
    // compensate for zero element.
    if ( ans-1 > 6)
    {
        printf("out of bounds\n");
        return -1;
    }
    else
    {
        fread(&data2[ans-1].l, sizeof(double), 1, fp2);
        fread(&data2[ans-1].c, sizeof(double), 1, fp2);
        fread(&data2[ans-1].v, sizeof(double), 1, fp2);
        fread(&data2[ans-1].td, sizeof(double), 1, fp2);
        fread(&data2[ans-1].pc, sizeof(double), 1, fp2);
    }








printf("%lf\n",data2[ans-1].l);
findRoot(data2,ans,&root);


fclose(fp2);
return 0;


}


void findRoot(INFO data2[] , int sel , double *root)
{
sel = sel -1;
    double upper = sqrt(4*data2[sel].l/data2[sel].c) ;
    double lower = 0;
    double x0 , x1 ;
    double sol , sol1;


    x0=upper;
    x1= lower;


    sol = func(data2,sel,x0);
    sol1 = func(data2,sel,x1);


if(func(data2,sel,x0)* func(data2,sel,x1) < 0)
{
    do
  {


    *root = (x0+x1)/2;


    if(func(data2,sel,*root)*func(data2,sel,x1) < 0 )
     x0 = *root;
    else x1 = *root;






}while(fabs(func(data2,sel,*root)*func(data2,sel,x1)) >  EPSILON);


}








}


double func(INFO data[] ,int sel , double x)
{
   double root;






   root = exp(-(x*data[sel].td)/(2*data[sel].l));
   root = root - data[sel].pc ;






 return(root);




}

when i run the program and created a bin file , then close it and try to read from it again , between closing the program and restarting it something seems to go wrong and also Thanks I have checked post 10 , the file is present in this case.