Thread: array of inputs gets overwritten (binary file reading)

this program read from file then asks the user if he wants to choose saved inputs or enter new ones , then after file is closed it will open the binary file created by it and ask the user if he wishes to pick one of the values previously entered or enter new ones

The problem is :
If the user chooses to enter new values the program will overwrite the old values in data2[0] , so if the user picks the 1st set of values it's actually going to be the 2nd set of values because the the 1st got overwritten.

Also , I keep getting an error that function " access" is implicit , what does that mean ?


PLEASE IGNORE EVERYTHING UNDER MAIN , I JUST POSTED SO YOU CAN SEE THE WHOLE CODE , IT'S UNRELATED TOT HE PROBLEM

Code:

#include <stdio.h>
#include <math.h>
#include <gng1106plplot.h>
#include <float.h>
#include <ctype.h>


#define NUM_POINTS 1000 // number of points
#define X_IX 0           // Row index for storing x values
#define FX_IX 1
#define TRUE 1
#define FALSE 0
#define EPSILON 1e-10
#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(INFO [], int,double *);
double func(INFO [],int , double);
double pfunc(double , int , double , INFO [] );
void plot(int numPoints, double points[][numPoints]);
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 (access( BINFILE, 0 ) != -1 )
     {
         fp2 = fopen(BINFILE, "ab+");
         printf("Do you want to choose previously inputted values? (y/n)\n");
         fflush(stdin);
         scanf("%c",&ans2);


         if (ans2 == 'y')
            flag = TRUE;
     }
    else fp2 = fopen(BINFILE, "ab+");




    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);


        if(check < 0)
        {
           flag2 = FALSE;
           printf("Invalid input , Please enter a bigger value for td\n");
        }
        if(50/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);


    rewind(fp2);


    // compensate for zero element.
    if ( ans-1 > 5)
    {
        printf("out of bounds\n");
        return -1;
    }
    else
    {
        fread(data2, sizeof(data2), ans, fp2);


    }










findRoot(data2,ans,&root);
printf("The value of the Resistor is %lf Ohms\n",root);


plotFunc(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 ;


    x0=upper;
    x1= lower;




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);




}


void plotFunc(INFO data2[], int sel, double *root)
{
    int ix;
    double inc;
    double points[2][NUM_POINTS];
    double x;


    inc = data2[sel-1].td/1000;
    for(ix = 0 ; ix < NUM_POINTS ; ix = ix+1)
    {


    points[X_IX][ix] = x;           // Save x value
       points[FX_IX][ix] = pfunc(x,sel-1,*root,data2);  // Calculate and save f(x) value
       x = x + inc;                   // update x value for next iteration
    }
    plot(NUM_POINTS, points);


}


double pfunc(double x,int index,double root ,INFO array2[] )
{
    double fx;


    fx = (array2[index].v*array2[index].c)*exp((-root*x)/(2*array2[index].l))*cos(sqrt((1/(array2[index].l*array2[index].c))-pow((root/(2*array2[index].l)),2))*x);
    return(fx);




 return(fx);




}


void plot(int numPoints ,double points[][numPoints] )
{
    // Variable declaration
    double minFx, maxFx;  // Minimum and maximum values of f(x)
    // Setup plot configuration
    plsdev("wingcc");  // Sets device to wingcc - CodeBlocks compiler
    // Initialize the plot
    plinit();
    // Configure the axis and labels
    plwidth(3);          // select the width of the pen
    minFx = getMin(points[FX_IX], numPoints);
    maxFx = getMax(points[FX_IX], numPoints);
    plenv(points[X_IX][0],points[X_IX][numPoints-1],
	      minFx, maxFx, 0, 0);
    plcol0(GREEN);           // Select color for labels
    pllab("x", "f(x)", "Plot of f(x) versus x");
        // Plot the function.
    plcol0(BLUE);    // Color for plotting curve
    plline(numPoints, points[X_IX], points[FX_IX]);
    plend();
}


double getMin(double *array, int n)
{
    int ix;
    double min = array[0];
     min = DBL_MAX;
    for(ix = 1; ix < n; ix = ix +1)
        if(min > array[ix]) min = array[ix];
    return(min);
}


double getMax(double *array, int n)
{
    int ix;
    double max = array[0];
    max = -DBL_MAX;
    for(ix = 1; ix < n; ix = ix +1)
        if(max < array[ix]) max = array[ix];
    return(max);
}

Code:

   if (access( BINFILE, 0 ) != -1 )

Code:

Kamal_Joub_binary_read_write.c:58:10: warning: implicit declaration of function 'access' [-Wimplicit-function-declaration]

their is nothing to tell the compiler what 'access' is so it can use it. That is the only mention of the word 'access' within your program. If you had a function called access then removed it, well that'd be why you're getting that error now.