Question

Im doing C homework and trying to get this program to run, but I get this:

Can anyone please run this and see if you get the same? (Change the output directory for the text files)

I’ve been trying for a long time and just cannot do it:

Here’s the code:

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

/////////////////
#define SIZE 2
/////////////////

struct Stock
{
    char name[10];
    int numShares;
    float buyShare,currPrice,fees;
    float initCost,currCost,profit;
};

/* Load the data from the keyboard and calculates 
the Initial Cost, Current Cost, and Profit 
for each stock via an array */

void load(struct Stock s[], int n) 
{
    char nameCompare[30] = "Open the bay doors";
    int i;
    for(i=0;i<n;i++)
    {
        printf("Enter the Stock Name\n");
        printf(">");
        gets(s[i].name);

        /////////////////////////////////////
        if(strncmp (s[i].name,nameCompare,10) == 0)
        {
            printf("\tI'm sorry, Dave, I'm afraid I can't do that\n");
            Sleep(3000);
            exit(1);
        }

        /////////////////////////////////////
        printf("Enter the Number of Shares\n");
        printf(">");
        scanf("%d", &s[i].numShares);
        printf("Enter the Buying Price Per Share\n");
        printf(">");
        scanf("%f", &s[i].buyShare);
        printf("Enter the Current Price Per Share\n");
        printf(">");
        scanf("%f", &s[i].currPrice);
        printf("Enter the Yearly Fees\n");
        printf(">");
        scanf("%f", &s[i].fees);

        s[i].initCost = (float)s[i].numShares * s[i].buyShare;
        s[i].currCost = (float)s[i].numShares * s[i].currPrice;
        s[i].profit = s[i].currCost - s[i].initCost - s[i].fees;
        fflush(stdin);
    }
}

/* Sort the array of structures 
on stock name and print the array 
after the sort is completed */

void sort(struct Stock s[], int n)
{
    Stock t;
    for(int i=0;i<n-1;i++)
        for(int j=0;j<n-1;j++)
            if(strcmp(s[j].name, s[j+1].name)>0)
            {
                t=s[j];
                s[j]=s[j+1];
                s[j+1]=t;
            }
}

/* Calculate and print the total profit for all of the stocks. 
That is, find the sum of the 5 profits for each stock. In 
addition, find and print out the number of stocks that 
had a positive profit, the number of stocks that had a 
negative profit, and the number of stocks that broke 
even, that is had a profit of $0.00 */

void calc(struct Stock s[],int n)
{
    float total=0;

    int Pos=0;
    int Neg=0;
    int Even=0;

    for(int i=0;i<n;i++)
    {
        total +=s[i].profit;
        if (s[i].profit>0)
            ++Pos;
        else if (s[i].profit<0)
            ++Neg;
        else
            ++Even;
    }

    printf("\n");
    printf("%d of stocks broke Positive\n",Pos);
    printf("\t%d of stocks broke Negative\n",Neg);
    printf("\t\t%d of stocks broke Even\n",Even);
    printf("\n");
    printf("The Total Trofit is $%f\n", total); //Check output
    printf("\n");
}
//Output of the calc function
void print(struct Stock s[], int n)
{
    for(int i=0;i<n;i++)
    {
        printf("\n");
        printf("The stock is %s\n", s[i].name);
        printf("\tWith Initial cost of $%0.2f\n", s[i].initCost);
        printf("\t\tCurrent cost is $%0.2f\n", s[i].currCost);
        printf("\t\t\tAnd your Profit is $%0.2f\n", s[i].profit); //Check output
        printf("\n");
    }
}
//Save the array of structures to a text file.
void savetext(struct Stock s[], int n)
{
    FILE *f;
    f = fopen("c:\\cs36\\textfile.txt","w"); 
    int i;
    for(i=0;i<n;i++)
    {
        fprintf(f,"%s\n",s[i].name);
        fprintf(f,"%d  %f  %f  %f  %f  %f  %f\n", s[i].numShares, s[i].buyShare, s[i].currPrice, s[i].fees, s[i].initCost, s[i].currCost, s[i].profit);
    }
    fclose(f);
}
//Retrieve and print the text file.
void loadtext(struct Stock s[], int n)
{
    FILE *f;
    f = fopen("c:\\cs36\\textfile.txt","r");
    for(int i=0;i<n;i++)
    {
        fgets(s[i].name, sizeof(s[i].name), f);
        fscanf(f, "%d%f%f%f%f%f%f\n", &s[i].numShares, &s[i].buyShare, &s[i].currPrice, &s[i].fees, &s[i].initCost, &s[i].currCost, &s[i].profit);
    }
    fclose(f);
}
//Save the array of structures to a binary file.
void savebin(struct Stock s[], int n)
{
    FILE *f;
    f = fopen("c:\\cs36\\binfile.bin","wb");
    if(! f)
    { 
        printf("Could not open the file");
        exit(1); 
    }
    else
        fwrite(&s, sizeof(s[10]), n, f);
    fclose(f);
}
//Retrieve and print the binary file.
void loadbin(struct Stock s[], int n)
{
    FILE *f;
    f = fopen("c:\\cs36\\binfile.bin","rb");
    if (! f)
    { 
        printf("Could not open the file");
        exit(1); 
    }
    else
        fread(&s, sizeof(s[10]), n, f);
    fclose(f);
}

int main (void)
{
    printf("Hello, Dave\n");
    Stock s[SIZE];
    load (s, SIZE);
    sort (s, SIZE);
    savetext (s, SIZE);
    savebin (s, SIZE);
    print (s, SIZE);
    calc (s, SIZE);
    loadtext (s, SIZE);
    print (s, SIZE);
    loadbin (s, SIZE);
    print (s, SIZE);
    system("PAUSE");
}

This is C, using Visual C++ 2008 Express

Answer 1

You are trying to access the null pointer.So that it will throw this error.

    fprintf(f,"%s\n",s[i].name);

In these line, s[i] may be null for some cases in your program so you are trying to access the member variable of the object which is NULL.

So only it is throwing this runtime error.