CODEWITHSUNDEEP
cexceptionprintfaccess-violation
Ryan Zaugg
Ryan Zaugg

Reputation: 39

sprintf "access violation reading location" exception

I'm taking a programming class in C, and I've run into a bug I can't solve no matter how hard I try.

The program instructs me to: "Ask the user for the first 12 digits of an EAN number, then calculate the 13th "security" digit by performing the following operations:

Add the second, fourth, sixth, eighth, tenth, and twelfth digits Add the first, third, fifth, seventh, ninth, and eleventh digits Multiply the first sum by 3 and add it to the second sum Subtract 1 from the total Compute the remainder when the adjusted total is divided by 10 Subtract the remainder from 9

I'm coming from Python, so the easiest way to split the number into it's individual digits is to convert it to a string and then revert each element in the character array to an int stored in an integer array.

Here's my code so far:

#include <stdio.h>

int main(void)
{
    long ean;       //creates variable to store a 12 digit integer
    int digits[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; //initializes a 1x12 integer array
    printf("Please enter the first 12 digits in your EAN: ");
    scanf_s("%ld", &ean);   //collects the appropriate user input and stores it in ean
    char seperated[12];     //creates character array
    **sprintf_s(seperated, "%ld", ean); //converts the long integer ean to a string called separated
    for (int i = 0; i < 12; i++)
    {
        sscanf_s(seperated[i], "%d", &digits[i]);   //iterates through the characters and converts each one to an integer
                                                    //stored in the array created earlier
        printf("%d\n", digits[i]);
    }
    int sumEvens = digits[1] + digits[3] + digits[5] + digits[7] + digits[9] + digits[11]; //sums the even digits
    int sumOdds = digits[0] + digits[2] + digits[4] + digits[6] + digits[8] + digits[10]; //sums the odd digits

    int total = (3 * sumEvens + sumOdds)-1;     //multiplies the first sum by 3 and adds it to the second sum, 
                                                //then subtracts one from the total
    int securityDigit = 9 - (total % 10);   //Computes the remainder when the total is divided by 10 and subtracts that from 9
    return 0;
}

The problem is, my sprintf statement (marked with **) is throwing an exception saying

Exception thrown at 0x0FB7373A (ucrtbased.dll) in ECE1400_2.exe: 0xC0000005: Access violation reading location 0xBE991A6D.

Does anyone know what I'm doing wrong and how I can fix it? I hope it's just something little, but I've been staring at this and researching for well over 2 hours.

Upvotes: 0

Views: 298

Answers (3)

Hermanto Kho
Hermanto Kho

Reputation: 46

there's a lot of unnecessary part.

int main()
{
    char s[12] = {0};
    int n = 0;
    int digits[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; //initializes a 1x12 integer array
    printf("Please enter the first 12 digits in your EAN: ");
    for (int i = 0; i < 12; i++)
    {
        scanf("%d", &digits[i]);
    }
    int sumEvens = digits[1] + digits[3] + digits[5] + digits[7] + digits[9] + digits[11]; //sums the even digits
    int sumOdds = digits[0] + digits[2] + digits[4] + digits[6] + digits[8] + digits[10]; //sums the odd digits

    int total = (3 * sumEvens + sumOdds)-1;     //multiplies the first sum by 3 and adds it to the second sum, 
                                                //then subtracts one from the total
    int securityDigit = 9 - (total % 10);   //Computes the remainder when the total is divided by 10 and subtracts that from 9
    
    for (int i = 0; i <= 11; i++) {
        n += sprintf (&s[n], "%d", digits[i]);
    }

}

Upvotes: 2

Jabberwocky
Jabberwocky

Reputation: 50778

This would be a start:

int main(void)
{
  __int64  ean;                       // using 64 bit integer

  int digits[12] = { 0 };             // one zero is enough

  printf("Please enter the first 12 digits in your EAN: ");
  scanf_s("%lld", &ean);              // using %lld here because ean is a 64 bit type
  char seperated[12];

  sprintf_s(seperated, 12, "%lld", ean); // also using %lld

  for (int i = 0; i < 12; i++)
  {
    digits[i] = seperated[i] - '0';   // I let you find out yourself about this "magic"
    printf("%d\n", digits[i]);
  }
  ...

Upvotes: 0

Lorale
Lorale

Reputation: 123

You probably want to do something like this

int main(void)
{
    int a[5]={1,2,3,1,3};
    char s[9] = {0};
    int n = 0;

    for (int i = 0; i < 5; i++) {
        n += sprintf (&s[n], "%d", a[i]);
    }

    printf ("\n char* s = %s\n\n", s);

    return 0;
}

instead of making it long.

and there's no need for you to use sscanf_s as mentioned in the comments.

Upvotes: 1

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