segmentation fault while trying to search

hello i am getting a segmentation fault right after i ask for the social security number in the print statement. i am not sure if the fault is in the search or recsearch function. please someone help

Code:

---

int srch (STUDENT student[], char* ssn)
{
 
  char* Name = "";
  int tempstu = -1; 

  while (strcmp(ssn, "q"))
  {
    printf("\n Please enter social security number (press q to quit): ");   
    scanf("%s", ssn);
    tempstu = recSrch(student, ssn, 0, SIZE - 1);
    printf("\nRecord found at index %d:", tempstu);
    strcat(strcat(strcpy(Name, student[tempstu].fName), " "),
student[tempstu].lName);
    printf("\n%30s %9d  %13s    %02d/%02d/%4d", Name,
            student[tempstu].grade, student[tempstu].ssn,
            student[tempstu].bDate.month, student[tempstu].bDate.date,
            student[tempstu].bDate.year);
}}
/*===============================recSrch=====================================*/
// this function searches for the input social security number and returns
// the result

int recSrch (STUDENT student[], char* ssn, int lb, int ub)
{
  int result;
  int mid = (lb + ub) / 2;

  if (lb > ub)
      {     
      result = -1;
      }
  else if (strcmp(ssn, student[mid].ssn) == 0)
          {
            result = mid;
          }   
  else if (strcmp(ssn, student[mid].ssn) < 0)
          {     
            result = recSrch(student, ssn, lb, mid - 1);
          }
  else
    {
    result = recSrch(student, ssn, mid + 1, ub);
    }
  return result;
}

---

oh and i am not even getting the print statement..."Record found at %d index"

Show more of your code. I think I know what the issue is but I need your code that calls the function to be certain.

Code:

---

#define MAX 20
#define SIZE 10

// creates a nested structure for student names, birthdates, and social
// security numbers
typedef struct
{
  int month;
  int date;
  int year;
} DATE;

typedef struct
{
  char fName[MAX];
  char lName[MAX];
  int grade;
  char ssn[11];
  DATE bDate;
} STUDENT;

/* prototype declarations */
bool openFile (FILE **fpinfile_txt, char* infile);
int convertMonth(char * monthStr);
int fillArr (FILE *fpinfile_txt, STUDENT* myStudents, int numRecords);
void sortArr(STUDENT student[], int last);
void exchangeSmallest (STUDENT student[], int i, int last);
void prtArr(STUDENT* student, int numRecords);
int srch (STUDENT student[], char* ssn);
int recSrch (STUDENT student[], char* ssn, int lb, int ub);

int main(int argc, char* argv[])
{
  STUDENT myStudents[SIZE];
  char *infile;
  int numRecords;
  int count;
 

  if (argc != 3)
  {
    printf("\nFile not found\n");
  }
    else
      {
      count = atoi(argv[1]);
      infile = argv[2];
        if (openFile (&fpinfile_txt, infile))
        {
          if(fillArr(fpinfile_txt, myStudents, count) != 1)
          {           
              prtArr(myStudents, count);
              sortArr(myStudents, count);
              prtArr(myStudents, count);
              srch(myStudents, ssn);
          }
        }
      }
  return 0;
}

---

Quote:

---

Originally Posted by starvinmarvin

Code:

---

#define MAX 20
#define SIZE 10
 
// creates a nested structure for student names, birthdates, and social
// security numbers
typedef struct
{
  int month;
  int date;
  int year;
} DATE;
 
typedef struct
{
  char fName[MAX];
  char lName[MAX];
  int grade;
  char ssn[11];
  DATE bDate;
} STUDENT;
 
/* prototype declarations */
bool openFile (FILE **fpinfile_txt, char* infile);
int convertMonth(char * monthStr);
int fillArr (FILE *fpinfile_txt, STUDENT* myStudents, int numRecords);
void sortArr(STUDENT student[], int last);
void exchangeSmallest (STUDENT student[], int i, int last);
void prtArr(STUDENT* student, int numRecords);
int srch (STUDENT student[], char* ssn);
int recSrch (STUDENT student[], char* ssn, int lb, int ub);
 
int main(int argc, char* argv[])
{
  STUDENT myStudents[SIZE];
  char *infile;
  int numRecords;
  int count;
 
 
  if (argc != 3)
  {
    printf("\nFile not found\n");
  }
    else
      {
      count = atoi(argv[1]);
      infile = argv[2];
        if (openFile (&fpinfile_txt, infile))
        {
          if(fillArr(fpinfile_txt, myStudents, count) != 1)
          {           
              prtArr(myStudents, count);
              sortArr(myStudents, count);
              prtArr(myStudents, count);
              srch(myStudents, ssn);
          }
        }
      }
  return 0;
}

---

---

What the... Where is this declared?

lol, I was thinking about posting this, but you beat me to it, starvin. Basically what's wrong is it's supposed to return the correct social security number when input along with the name and index, quit the function if you type in q, or say that no record was found if you put in a number that's not in the search. Do you guys think the problem is in any of these functions or could they be in another function?

Code:

---

int fillArr (FILE *fpinfile_txt, STUDENT* myStudents, int numRecords)
{

  int i;
  int scanRes;
  int stop = 0;
  int error = 0;
  char fName[MAX];
  char lName[MAX];
  int grade;
  char ssn[MAX];
  char month[MAX];
  int date;
  int year;

---

Ok. As I kind of suspected....

Code:

---

int srch (STUDENT student[], char* ssn)
{
  char* Name = "";//NO!
  int tempstu = -1; 

  while (strcmp(ssn, "q"))//NO!

  {
    printf("\n Please enter social security number (press q to quit): ");   
    scanf("%s", ssn);
    tempstu = recSrch(student, ssn, 0, SIZE - 1);
    printf("\nRecord found at index %d:", tempstu);
    strcat(strcat(strcpy(Name, student[tempstu].fName), " "), student[tempstu].lName);
    printf("\n%30s %9d  %13s    %02d/%02d/%4d", Name,
            student[tempstu].grade, student[tempstu].ssn,
            student[tempstu].bDate.month, student[tempstu].bDate.date,
            student[tempstu].bDate.year);
  }
}

---

What you are wanting to do is something like this:

Code:

---

int srch (STUDENT student[], char* ssn)
{
  char Name[256] = "";
  int tempstu = -1; 

  ssn[0] = '\0';

  while (strcmp(ssn, "q"))
  {
    printf("\n Please enter social security number (press q to quit): ");   
    scanf("%9s", ssn);
    tempstu = recSrch(student, ssn, 0, SIZE - 1);
    printf("\nRecord found at index %d:", tempstu);
    strcat(strcat(strcpy(Name, student[tempstu].fName), " "),  student[tempstu].lName);
    printf("\n%30s %9d  %13s    %02d/%02d/%4d", Name,
            student[tempstu].grade, student[tempstu].ssn,
            student[tempstu].bDate.month, student[tempstu].bDate.date,
            student[tempstu].bDate.year);
  }
}

---

wait i forgot i changed it after that
here is where it is declared

Code:

---

int main(int argc, char* argv[])
{
  char* ssn = " ";
  STUDENT myStudents[SIZE];
  char *infile;
  int numRecords;
  int count;
  FILE *fpinfile_txt;

---

Ok. That is even more like what I suspected you had done :) I was worried that I totally lost my mind!

char ssn[MAX] = ""; is how it should be declared.

ok i tried that but now i get a invalid initliazer for char* [256] = "";

Then you didn't "try that" -- if you had, there wouldn't be an * in your error message.

Perhaps I should make my entire posts bolded sometime just to see what happens...

Since "why" is always more useful than shouting "NO!" at someone, though infinitely less fun. Here is the deal, when you say char *x = "y" you are pointing x to a string stored somewhere in your program. When you say char x[20] = "" you are saying I have an array of 20 chars named x, and I wish to fill it with "". Make sense? So when you start trying to write to that place where there is a string "y" you are going to also be buffer overflowing into god only knows what.

thanks it got rid of the segmentation fault however now it says
something like

Record found at index -1
with some weird charcters and 42 P 00/-173943938493/27

I never said your other code was necessarily right :) My eyes just sort of automatically wander to potential segfaults when I am approached with "Aaaah!! My s*** is broke!"

I am not sure that your search necessarily works as you intend for it to. It only searches one direction, right? Perhaps if it searched both before the mid point and the beginning as well as between the mid point and end, you would be in good shape :)

Okay, I put in

Code:

---

char* ssn[MAX] = "";

---

and got

Code:

---

error: invalid initializer

---

For that line. Is there somewhere else in one of the other functions that needs this
char * ssn[MAX] = "" ?

EDIT: Whoops. I found out the problem. I accidentally put in char* instead of just char.

got it to work.

i am not really understanding master 5001...could you post code

Same here. I thought our function already searched both ways like you said. I had no idea it was only searching one way. Wouldn't that just be sequential search? I thought ours was in binary.

Quote:

---

Originally Posted by master5001

I am not sure that your search necessarily works as you intend for it to. It only searches one direction, right?

---

I vote for "wrong". How sure are you that the SSN's in the array are correct?

Well it's supposed to be reading the arrays from a file, I believe, so whatever is in the file is what the SSNs are.

nevermind i figrued it out....thanks..

Okay, part of it works...one part to be exact.

Here's the output for all the SSNs that I searched. Only the last one worked:

q did make the program exit, but it still output a bunch of random numbers and symbols.

Here's the output:

Code:

---

Please enter social security number (press q to quit): 444-44-4444

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
 Please enter social security number (press q to quit): 555-55-5555^H

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
 Please enter social security number (press q to quit): 555-55-5555

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
 Please enter social security number (press q to quit): 111-11-1111

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
 Please enter social security number (press q to quit): 888-88-8888

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
 Please enter social security number (press q to quit): 222-22-2222

Record found at index 4:
            Marsupial Platypus        6    222-22-2222    05/16/1975
 Please enter social security number (press q to quit): q

Record found at index -1:
                        0ùÿ¿        42            P    00/-1073742860/ 127
Thank You.-bash-3.00$

---

Well, if you're printing the -1 index, you had better expect complete gibberish. It doesn't exist, after all, so it's not like you can put something meaningful in it.

Are those other SSNs supposed to be in the file?

Yes, all of them are in the file.

I'm wondering if this has anything to do with it:

Code:

---

if (lb > ub)
      {
      result = -1;

---

Several possibilities:

1) The SSNs are in the file, but they're not in your structs (i.e., you are reading incorrectly).

B) The data is not sorted by SSN, making binary searching on the SSN impossible.

III) Something else.

Yeah, it's weird. It's only printing the last index in the sorted list.

Here is the list:

Code:

---

                      Jane Doe        5    444-44-4444    09/27/2000
                      John Doe        4    555-55-5555    11/02/1976
                Justin Johnson        5    111-11-1111    02/02/1977
                Justin Johnson        3    888-88-8888    10/28/2000
            Marsupial Platypus        6    222-22-2222    05/16/1975

---

Quote:

---

Originally Posted by The Monkey King

I'm wondering if this has anything to do with it:

Code:

---

if (lb > ub)
      {
      result = -1;

---

---

Well, kind of. That's where the -1 index is coming from, obviously. However taking this line out would make your binary search (well, anybody's binary search) completely and irretrievably broken, as this the only way you stop searching (unless you luck into finding the actual data, which you haven't been doing).

If you believe that this is sorted:
444-44-4444
555-55-5555
111-11-1111
888-88-8888
222-22-2222

then I've got some prime beachfront property in Arizona to sell you.

(In other words, we appear to be in option "B".)

Would this rule out the first possibility?

Code:

---

typedef struct
{
  int month;
  int date;
  int year;
} DATE;

typedef struct
{
  char fName[MAX];
  char lName[MAX];
  int grade;
  char ssn[11];
  DATE bDate;
} STUDENT;

---

Okay, so it's B, sorry I must've posted at the same time as you.

Quote:

---

Originally Posted by The Monkey King

Would this rule out the first possibility?

Code:

---

typedef struct
{
  int month;
  int date;
  int year;
} DATE;

typedef struct
{
  char fName[MAX];
  char lName[MAX];
  int grade;
  char ssn[11];
  DATE bDate;
} STUDENT;

---

---

No -- in fact it guarantees it. 1) Just because you have storage for it, doesn't mean you are using it correctly, and we know you are using it incorrectly because 2) it is impossible to get "111-11-1111" into a char[11], since it contains 12 characters -- that '\0' at the end is MOST DEFINITELY needed for strcmp.

So now we know that both 1 and B are traps you have fallen into. We'll see if we can dig up something for III later.

So could this be the problem?

Code:

---

void sortArr(STUDENT student[], int last)
{
  int i;
     
  for (i = 0; i < last - 1; i++)
    exchangeSmallest (student, i, last);
         
  return;
}

---

So in the typedef struct it should be

Code:

---

char ssn[12];

---

?

Quote:

---

Originally Posted by The Monkey King

So could this be the problem?

Code:

---

void sortArr(STUDENT student[], int last)
{
  int i;
     
  for (i = 0; i < last - 1; i++)
    exchangeSmallest (student, i, last);
         
  return;
}

---

---

The for loop probably isn't a problem; but you'll need to make sure, if you want to search on SSN, that exchangeSmallest sorts on SSN. What you posted was sorted by first name.

Oh, I see. Okay, I remember having this problem earlier today about sorting the names. So for now I just have to switch the first name with the ssn, right?

ExchangeSmallest needs to look at the ssn field, which should be a char[12], yes.

Oh, hang on a second. The instructions say that it should be sorted by last name, then first name, then (if both of those are the same) SSN. So basically, it's sorted the same way as my professor's example output, which I guess is correct. So how do I search for the correct indexes for SSN if SSNs are the last priority in sorting?

Then you'll have to search linearly -- start at the beginning, and examine each one until (1) you find it or (2) you run off the end of your array.

You mean sequential search (We never went over linear searching if that's what it's called)?

Same deal.

Okay.

Oh, crap. It looks like the instructions demand binary search.

Quote:

---

Provide the ability for the user to interactively search for records based
on social security number, accomplished via a recursive implementation of
binSrch(). The program should prompt the user for social (including -s)...

---

So if SSNs are last in priority in sorting, is searching for it using a binary recursive search function even possible?

Well, now you have two options.

1) If the user wants to search, re-sort based on social security number, do the search, and then sort back again by name.

2) Gently (gently!) inquire of your instructor whether he's been feeling well lately, and has he been taking things to help, etc.

lol, I wish I could do the second part of what you said, but unfortunately my instructor's inbox is full and she's never at school, plus it's due at 8 AM tomorrow so not much I can do in that category.

Oh and I got it to work. Actually, my partner starvinmarvin did, but there's still one problem. If I type in a number that doesn't exist or just type 'q' I get a segmentation fault.

I got it to work.

You have to make sure you don't just keep walking off the end of the array. If lb > ub, you still need to stop.

So do I need a separate if-else statement or a loop (for loop)? Maybe a while loop?

Yes! It works! Thanks for the help everyone!