Thread: 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;
}

ok i tried this and it gave me a bunch of 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

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

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");