Thread: my second program

So this is my second real program. It calculates the Improved Euler method - or is supposed to.

When it runs the user types in either, recent - which loads the last data from a text file, or data, which allows them to enter the start values.

If you type data, it should then ask for you to enter a, b, c, Xo, Yo, Zo.

But for some reason, which i cant figure, it crashed when you press enter after typing either of these. I think its a problem with the Euler Function - possibly because I am trying to pass it strings in the wrong way.

Please could someone have a look.

I;m pretty new to this so my commenting and indenting is pretty poor. Please bear with me:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <Windows.h>

int main()
{
    char  *as[100], *bs[100], *cs[100], *Xos[100], *Yos[100], *Zos[100], *filename[20];//the s at the end of the name tell me it is stored as a string.

    FILE  *recentdata, *EulerData;//pointer to store recent data in text file.
while (1)
{
    menu();


    //if the user typed in data, it will bring them back to here.

    printf("Please enter the data");
    printf("A:");
    scanf("%99s", as);
    printf("B:");
    scanf("%99s", bs);
    printf("C:");
    scanf("%99s", cs);
    printf ("%s %s %s\n\n", as, bs, cs);

    printf("Please input Xo, Yo and Zo\n");
    printf("Xo:");
    scanf("%99s", Xos);
    printf("Yo:");
    scanf("%99s", Yos);
    printf("Zo:");
    scanf("%99s", Zos);
    printf ("%s %s %s\n\n", Xos, Yos, Zos);

    recentdata = fopen("recentdata.txt", "w");
    fprintf(recentdata, "%s %s %s %s %s %s\n", as, bs, cs, Xos, Yos, Zos);
    fclose;





        printf ("\n a = %.2s\n b = %.2s\n c = %.2s\nXo = %.2s\nYo = %.2s\nZo = %.2s\n", as, bs, cs, Xos, Yos, Zos);

        Sleep(1000);
        printf("\nPlease enter the name of the file to store the data in\n");
        printf("If it doesnt exist, it will be created.\n\n");
        scanf("%s", filename);
        printf("\nStoring all Data in file '%s.txt'\n", filename);
        Sleep(1000);
        printf("Beginning execution of improved Euler...\n\n");
        Sleep(1000);

        //send Euler function the relevent variables.
        Euler(as, bs, cs, Xos, Yos, Zos);


}
return 0;
}

int menu()
{

    printf("\nType 'recent' to use the last entered data or:\nInput a, b and c, hitting Enter between each one,\n");
    printf("Typing 'q' at any time will bring you back here,\n");
    printf("To exit the program, from here type 'exit'.\n\n");
    user_command();

return 0;
}

int Euler(t, u, v, x0, y0, z0)

    char t, u, v, x0, y0, z0;
    {
        float x[100], y[100], z[100], dxdt_i, dydt_i, dzdt_i,dx, dy, dz, dxdt_new, dydt_new, dzdt_new, dt = 1;
        float a, b, c, Xo, Yo, Zo;
        int i;

        a=atof(t); //converting strings to floats so that the compiler understands it is a number that can be used mathematically.
        b=atof(u);
        c=atof(v);
        Xo=atof(x0);
        Yo=atof(y0);
        Zo=atof(z0);

        x[0] = Xo;
        y[0] = Yo;
        z[0] = Zo;

        system("cls");
        printf ("\nLorenz formulas:\n\n");
        printf("dx                          dy                             dz \n");
        printf("--  = a(y - x)       :      --  = x(b - z) - y      :      --  = xy - cz\n");
        printf("dt                          dt                             dt\n\n\n");


        for (i = 0; i<101; i++)
        {

        dxdt_i = t*(y[i] - x[i]);
        dydt_i = x[i]*(u - z[i]) - y[i];
        dzdt_i = (x[i]*y[i]) - (v*z[i]);

        dx = (t*(y[i] - x[i]))*dt;
        dy = (x[i]*(u - z[i]) - y[i])*dt;
        dz = ((x[i]*y[i]) - (v*z[i]))*dt;


        dxdt_new = t*(y[i] - (x[i] + dx));
        dydt_new = x[i]*(u - z[i]) - (y[i] + dy);
        dzdt_new = (x[i]*y[i]) - (v*(z[i] + dz));

        x[i+1] = x[i] +(dt/2)*(dxdt_i + dxdt_new);
        y[i+1] = y[i] +(dt/2)*(dydt_i + dydt_new);
        z[i+1] = z[i] +(dt/2)*(dzdt_i + dzdt_new);

        printf("dx                          dy                             dz\n");
        printf("--  = %5.2f  :      --  = %5.2f  :      --   = %5.2f\n", dxdt_i, dydt_i, dzdt_i);
        printf("dt                          dt                             dt\n");
        printf("\nnew xgrad = %.3f new ygrad = %.3f new zgrad = %.3f\n\n", dxdt_new, dydt_new, dzdt_new);
        printf("\nnew x = %.3f new y = %.3f new z = %.3f\n\n", x[i+1], y[i+1], z[i+1]);

       i =  i++;
    }
    }

int user_command()
{
    char *options[100];
    FILE *recent;
   char *af[100], *bf[100], *cf[100], *Xof[100], *Yof[100], *Zof[100];
    //function decides what to do based on user input

    scanf("%99s", options);

    //What to do if user types exit
    if(strcmpi(options,"exit") == 0)//compare options to "recent" NOT case sensitive.
    {
        exit(0);

    }

    //What to do if user types q
    else if(strcmpi(options,"q") == 0)//compare options to "recent" NOT case sensitive.
    {
        system("cls");
        menu();

    }

    //What to do if user types recent
    else if(strcmpi(options,"recent") == 0)//compare options to "recent" NOT case sensitive.
    {
            recent = fopen("recentdata.txt", "r");
            fscanf (recent, "%s %s %s %s %s %s", af, bf, cf, Xof, Yof, Zof);
            fclose;
           
            Euler(af, bf, cf, Xof, Yof, Zof);



    }
    else if (strcmpi(options,"data") == 0)
{
    return(0);
}
}

it crashed when you press enter after typing either of these

use getchar after each scanf to get ride of the \r , thats why *i think you program crashes
cause it stores inappropriate values

Just saying, its not good programming practice to have functions start with a capital letter.

OK will get rid of capital letters but as vart said, why?

where is the \r?

what will getchar do, how is it used?

In your user_command function, you don't have any space to store the data that the user types in. Perhaps you meant "char options[100]" instead?

you have a i=i++ in your code and thats not good.
do i=i+1;
or just use i++; alone but never i=i++ or i++ = i;

that way of increment and decrement is is something that make the program unstable and crash