Search through a struct.

[colinuk]

Hi Guys,

Im using Borland 4.5 on WinXP

I have a fuction i want to call to search through the records in a struct.

If the string passed was there then Return 1; if the string is not there or there are no records then return 0;


At the moment the program just hangs/crashes so im not realy sure where in the code the error lies.

If anyone can have a look through my code and point me in the right direction Id be very gratefull.
Regards as ever
C

My Code:

The code in the calling function

while (reg_available(record_id)!=1);
   {
   printf("Please RE-Enter A Reg No\n");
   fgets(record_id,sizeof(record_id),stdin);
   }

strcpy(students_database[index].reg_no, record_id);
printf("\nThis Registration ID Was Added\n");

The search function that called on:

/* Function to check the if the  ID/string has been added already */

char  reg_available(char*string1)
{
 int loop=0;
 int found=0;

     while(found == 0 && loop < index)
     {
             if( strcmp(students_database[loop].reg_no,string1) == 0)
            {
               printf("RECORD FOUND");
               return 0;
               found=1;
           }
              loop++;

    }

 if(found !=0 && loop == index)
   {
     printf("NOT FOUND\n");
   }
return 1;
}

[hk_mp5kpdw]

char  reg_available(char*string1) // You should be returning an int
{
 int loop=0;
 int found=0;

     while(found == 0 && loop < index)  // Unnecessary because of return below
     {
             if( strcmp(students_database[loop].reg_no,string1) == 0)
            {
               printf("RECORD FOUND");
               return 0;  // You said it should return 1 if found
               found=1;  // Pointless since you've already returned by this point
           }
              loop++;

    }

 // If we have reached this point we already know you haven't found the record,
 // the whole if test doesn't need to be done, just do the printf and return
 if(found !=0 && loop == index)
   {
     printf("NOT FOUND\n");
   }
return 1;  // You said it should return 0 if not found
}

[edit]Perhaps a more useful value to return would be an index where the match was found, a value in the range [0,index), and perhaps some negative value indicating error.[/edit]

[xxxrugby]

If it is from a file, I make like this in my code and is workig fine for me

 struct book {
     char name[30];
}data;
FILE *t;
t = fopen("book.txt", "rb+");
while(fread(&data, sizeof(data), 1, t) == 1)
    {
        if(strcmp(data.name, bookname, n) == 0)
            printf("%s\n", &data.name);
    }

[colinuk]

Thanks Ive made the alterations and now when a record is found it gets stuck in the loop and prints "Record Found" over and over till it crashes.


Here is what I have:

int reg_available(char*string1)
{
 int loop=0;


while(loop < index)
{
      if( strcmp(students_database[loop].reg_no,string1) == 0)
      {
      printf("RECORD FOUND");
                  return 0;

      }
    loop++;

}
    if(loop == index)
    {
    printf("NOT FOUND\n");
    }
    return 1;

[pianorain]

Post more code. This works:

struct struct_type
{
    char reg_no[5];
} students_database[1024];

int upperBound;

char reg_available(char* string1)
{
    int loop=0;
    
    while(loop < upperBound)
    {
        if (strcmp(students_database[loop].reg_no,string1) == 0)
        {
            printf("RECORD FOUND\n");
            return 0;
        }
        loop++;
        
    }

//You don't really need this if-statement    
    if(loop == upperBound)
    {
        printf("NOT FOUND\n");
    }
    return 1;
}

int main()
{
    char record_id[5];
    char ch;

//give me some test data
    strcpy(students_database[0].reg_no,"abcd");
    strcpy(students_database[1].reg_no,"efgh");
    strcpy(students_database[2].reg_no,"ijkl");
    strcpy(students_database[3].reg_no,"mnop");
    strcpy(students_database[4].reg_no,"qrst");
    upperBound = 5;

//go looking
    fgets(record_id,sizeof(record_id),stdin);
    while ((ch = getchar()) != '\n' && ch != EOF);

    while (reg_available(record_id)!=1)
    {
        printf("Please RE-Enter A Reg No\n");
        fgets(record_id,sizeof(record_id),stdin);
        while ((ch = getchar()) != '\n' && ch != EOF);
    }

    strcpy(students_database[upperBound].reg_no, record_id);
    printf("\nThis Registration ID Was Added\n");
    upperBound++;
}

I renamed your index variable to upperBound, but that should be the only change.

[colinuk]

If it is from a file, I make like this in my code and is workig fine for me

 struct book {
     char name[30];
}data;
FILE *t;
t = fopen("book.txt", "rb+");
while(fread(&data, sizeof(data), 1, t) == 1)
    {
        if(strcmp(data.name, bookname, n) == 0)
            printf("%s\n", &data.name);
    }

Thanks, the data is just held by the struct, i have no external file.

Thanks again
C

[colinuk]

Hey Guys,

Here is the full 2 functions code, Its running but its not quite right.

Perhaps you guys will see what im missing.

Thanks again

/*functions for adding a record... */

void add_new_student(void)

{
int key;
char record_id[40];
clrscr();

/* Add the name & ID to the database*/

printf("\n\n\t\t   Enter New Name And Reg No\n\n");
printf("Enter First Name: ");
gets(students_database[index].fname);
fflush(stdin);

printf("Enter Last Name: ");
gets(students_database[index].sname);
fflush(stdin);

printf("Please enter an 4 letter Reg No eg: w123 \n");
fgets(record_id,sizeof(record_id),stdin);

while(check_reg(record_id)!=1)
   {
   printf("Please RE-Enter A Reg No In The Correct Format eg: w123 \n");
   fgets(record_id,sizeof(record_id),stdin);
   }

printf("Reg ID %s Is In The Correct Format Now checking for avaliability \n",record_id);


/*check reg is available*/

while(reg_available(record_id)==0);
   {
   printf("Please RE-Enter A Reg No\n");
   fgets(record_id,sizeof(record_id),stdin);
   }

/*The string has passed so Add the string to the structs records*/

strcpy(students_database[index].reg_no, record_id);
printf("\nThis Registration ID Was Added\n");


printf("\nPlease Enter The Credits \n");
scanf("%d",&students_database[index].credit);
fflush(stdin);


while(students_database[index].credit <10)
{
printf("Credits are between 10-15 please choose again!");
scanf("%d",&students_database[index].credit);
fflush(stdin);
}

while(students_database[index].credit >15)
{
printf("Credits are between 10-15 please choose again!");
scanf("%d",&students_database[index].credit);
fflush(stdin);
}

key = getchar();

/* Increment the array */
index++;

}

/*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/

/* Function to check the if the  ID/string has been added already */

char reg_available(char*string1)
{
 int loop=0;


   while(loop < index)
   {
      if( strcmp(students_database[loop].reg_no,string1) == 0)
      {
      printf("RECORD FOUND");
      return 0;

      }
      loop++;

   }

if(loop == index)
  {
  printf("NOT FOUND\n");
  }
  return 1;
}
/*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/

[pianorain]

while(reg_available(record_id)==0); //Lose the semi-colon

[colinuk]

while(reg_available(record_id)==0); //Lose the semi-colon

Thanks, I never saw that...

It seems to be working great now.
Thanks a lot guys.
C