help needed for sorting nested loops...segmentation error

ok i have a project due wedsnday i am trying to sort a list of structures...when i run the program i get a segmentation fault..please help

Code:

void exchangeSmallest (STUDENT student[], int i, int last)
{
/* Local Definitions */   
   int walker;
   int smallest;
   STUDENT tempData = {"", "", 2, "123-45-6789", {0,0,0}};

/* Statements */
   smallest = i;
   for (walker = i + 1; walker <= last; walker++)
     if (strcmp(student[walker].lName, student[smallest].lName) == 0)
      {
       if (strcmp(student[walker].fName, student[smallest].fName) == 0)
        {
         if (strcmp(student[walker].ssn, student[smallest].ssn) < 0)
          {
           smallest = walker;
          }
        } 
        else
         {
           if (strcmp(student[walker].fName, 
               student[smallest].fName) < 0)
            {
              smallest = walker;
            } 
         }
      }
     else
      { 
        if (strcmp(student[walker].fName,
                student[smallest].fName) < 0)
         { 
             smallest = walker;
         } 
      }  
  
      strcpy(tempData.fName, student[i].fName);
      strcpy(tempData.lName, student[i].lName);
      tempData.grade = student[i].grade;
      strcpy(tempData.ssn, student[i].ssn);
      tempData.bDate.month = student[i].bDate.month;
      tempData.bDate.date = student[i].bDate.date;
      tempData.bDate.year = student[i].bDate.year;
      strcpy(student[i].fName, student[smallest].fName);
      strcpy(student[i].lName, student[smallest].lName);
      student[i].grade = student[smallest].grade;
      strcpy(student[i].ssn, student[smallest].ssn);    
      student[i].bDate.month = student[smallest].bDate.month;
      student[i].bDate.date = student[smallest].bDate.date;
      student[i].bDate.year = student[smallest].bDate.year; 
      strcpy(student[smallest].fName, tempData.fName);
      strcpy(student[smallest].lName, tempData.lName);
      student[smallest].grade = tempData.grade;
      strcpy(student[smallest].ssn, tempData.ssn);
      student[smallest].bDate.month = tempData.bDate.month;
      student[smallest].bDate.date = tempData.bDate.date;
      student[smallest].bDate.year = tempData.bDate.year; 
printf("%s", student[smallest].fName);
   return;
} 

/*===================================prtArr=================================*/
void prtArr(STUDENT* student, int numRecords)
{
   int i;
   char* Name;

   printf("\n%26sName     Level            SSN      Birthdate"," ");
   printf("\n%26s----     -----            ---      ---------"," ");


   for (i = 0; i < numRecords; i++)
     {
       strcat(strcat(strcpy(Name, student[i].fName), " "), student[i].lName);
       printf("\n%30s %9d  %13s     %02d/%02d/%4d",
             Name, student[i].grade, student[i].ssn,
             student[i].bDate.month, student[i].bDate.date,
             student[i].bDate.year);
     }
   printf("\n\n");

}

Well, I am really a bad "spotter" (generally), but could I suggest using a debugger? If you don't want/have just put printf("OK\n") at some points to see where you get the segfault or printf("%d\n") (always the \n) inside loops to see at what iteration there is the error

A hunch would be this line:

Code:

for (walker = i + 1; walker <= last; walker++)

particularly the <= ... I suspect that should be just <.

ya i tried... to put printf("&#37;s", student[smallest].fName); at the end of exchange smallest and it prints out like 2 first names and a last name after that that are all jumbled together...my infile is a list of names, grades, social, grades, and b-dates.

ok i tried the above comment to put just < and it says john,marsupial,justin,marsupial,marsupial but its not sorted

here is the module to sort right above this module

Code:

/*===================================sortArr=================================*/

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

   return;
}

Code:

       if (strcmp(student[walker].fName, student[smallest].fName) == 0)
        {
         if (strcmp(student[walker].ssn, student[smallest].ssn) < 0)
          {
           smallest = walker;
          }
        } 
        else
         {
           if (strcmp(student[walker].fName, 
               student[smallest].fName) < 0)
            {
              smallest = walker;
            } 
         }
      }
     else
      { 
        if (strcmp(student[walker].fName,
                student[smallest].fName) < 0)
         { 
             smallest = walker;
         } 
      }

This would be pretty inefficient, as you are comparing the exact same thing every time. How about:

Code:

   int fcmp;
...
       fcmp = strcmp(student[walker].fName, student[smallest].fName);
       if (fcmp == 0)
        {
         if (strcmp(student[walker].ssn, student[smallest].ssn) < 0)
          {
           smallest = walker;
          }
        } 
        else
         {
           if (fcmp < 0)
            {
              smallest = walker;
            } 
         }
      }
     else
      { 
        // Is this RIGHT?
        if (fcmp < 0)
         { 
             smallest = walker;
         } 
      }

I think the last if-statement should be different, comparing the last name, rahter than first name.

--
Mats

ok i tried this and it gave me a bunch of error messages

How about we all have a party at your house, and when we come over, you can show us the error messages?

haha sounds good...lol ok sytax error before the second else

nevermind it was a forgotten first bracket...i get the first names from the structure but they arent sorted

matsp probably typed it in off the top of his head and didn't do any syntax checking. Syntax checking, as might be typical for code snippets like this, is left for the reader.

ok ya the prgram runs but when i echo out the first names they arent sorted...it just gives them as they appear in the file that is opened

Aye mateee - post yer code. Arg...

Code:

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

   return;
}

/*===============================exchangeSmallest=============================*/

void exchangeSmallest (STUDENT student[], int i, int last)
{
/* Local Definitions */   
   int walker;
   int smallest;
   int fcmp;
   STUDENT tempData = {"", "", 2, "123-45-6789", {0,0,0}};

/* Statements */
   smallest = i;
   for (walker = i + 1; walker <= last; walker++)
        

       fcmp = strcmp(student[walker].fName, student[smallest].fName);
       if (fcmp == 0)
        {
         if (strcmp(student[walker].ssn, student[smallest].ssn) < 0)
          {
           smallest = walker;
          }
        } 
        else
         {
           if (fcmp < 0)
            {
              smallest = walker;
            } 
         }
      }
     else
      { 
        // Is this RIGHT?
        if (fcmp < 0)
         { 
             smallest = walker;
         } 
      }  
  
      strcpy(tempData.fName, student[i].fName);
      strcpy(tempData.lName, student[i].lName);
      tempData.grade = student[i].grade;
      strcpy(tempData.ssn, student[i].ssn);
      tempData.bDate.month = student[i].bDate.month;
      tempData.bDate.date = student[i].bDate.date;
      tempData.bDate.year = student[i].bDate.year;
      strcpy(student[i].fName, student[smallest].fName);
      strcpy(student[i].lName, student[smallest].lName);
      student[i].grade = student[smallest].grade;
      strcpy(student[i].ssn, student[smallest].ssn);    
      student[i].bDate.month = student[smallest].bDate.month;
      student[i].bDate.date = student[smallest].bDate.date;
      student[i].bDate.year = student[smallest].bDate.year; 
      strcpy(student[smallest].fName, tempData.fName);
      strcpy(student[smallest].lName, tempData.lName);
      student[smallest].grade = tempData.grade;
      strcpy(student[smallest].ssn, tempData.ssn);
      student[smallest].bDate.month = tempData.bDate.month;
      student[smallest].bDate.date = tempData.bDate.date;
      student[smallest].bDate.year = tempData.bDate.year; 
printf("&#37;s", student[smallest].fName);
   return;
} 

/*===================================prtArr=================================*/
void prtArr(STUDENT* student, int numRecords)
{
   int i;
   char* Name;

   printf("\n%26sName     Level            SSN      Birthdate"," ");
   printf("\n%26s----     -----            ---      ---------"," ");


   for (i = 0; i < numRecords; i++)
     {
       strcat(strcat(strcpy(Name, student[i].fName), " "), student[i].lName);
       printf("\n%30s %9d  %13s     %02d/%02d/%4d",
             Name, student[i].grade, student[i].ssn,
             student[i].bDate.month, student[i].bDate.date,
             student[i].bDate.year);
     }
   printf("\n\n");