🚀 go-pugleaf

Hi,

I didn't scan through the complete example but what makes me curious is
this:

strcpy(s[0].id, "1000001");

This will copy 8 characters (the 8'th char is the delimiting 0) to the
target.
BUT your target can hold only 7 chars. I expect this will overwrite the
next item in your struct. And subsequently trash something.

Roland


"EL" <lameddie@yahoo.com> wrote in message
news:a2um2g$1q1@imsp212.netvigator.com...
> Hi all,
>
> I want to pass a structure to my own function and change its value,
however
> i couldn't get the expected result. why?
>
> struct mystr
> {
> char id[7], name[21];
> };
>
> void appRec(mystr* , int&);
>
> void main()
> {
>   mystr s[50];
>   int i, j, b, ttl;
>   char vid[7], bid[7];
>
>   strcpy(s[0].id, "1000001");
>   strcpy(s[0].name, "RobertHi");
>   strcpy(s[1].id, "1000008");
>   strcpy(s[1].name, "KawaiiNic");
>
>   ttl = 2;
>   appRec(s, ttl);
>   for (i=0; i<ttl ; i++)
>   {
>    cout << "\nStud ID : " << s[i].id;
>    cout << "\tName    : " << s[i].name;
>   }
>
> }
>
> void appRec(mystr *s1, int &ttl)
> {
>   ttl++;
>   cout << "\nTotal in function: " << ttl;
>   strcpy(s1[ttl].id, "1000005");
>   strcpy(s1[ttl].name, "Minotaic");
>   int i=0;
>   for (i=0; i<ttl; i++)
>   {
>    cout << "\nStud ID fnt : " << s1[i].id;
>    cout << "\tName    fnt : " << s1[i].name;
>   }
> }
>
>

You are incrementing ttl in the wrong place. Try this.

Berend


void appRec(mystr *s1, int &ttl)
{
  cout << "\nTotal in function: " << ttl;
  strcpy(s1[ttl].id, "1000005");
  strcpy(s1[ttl].name, "Minotaic");
  ttl++;
  int i=0;
  for (i=0; i<ttl; i++)
  {
   cout << "\nStud ID fnt : " << s1[i].id;
   cout << "\tName    fnt : " << s1[i].name;
  }
}

--

"EL" <lameddie@yahoo.com> wrote in message
news:a2um2g$1q1@imsp212.netvigator.com...
> Hi all,
>
> I want to pass a structure to my own function and change its value,
however
> i couldn't get the expected result. why?
>
> struct mystr
> {
> char id[7], name[21];
> };
>
> void appRec(mystr* , int&);
>
> void main()
> {
>   mystr s[50];
>   int i, j, b, ttl;
>   char vid[7], bid[7];
>
>   strcpy(s[0].id, "1000001");
>   strcpy(s[0].name, "RobertHi");
>   strcpy(s[1].id, "1000008");
>   strcpy(s[1].name, "KawaiiNic");
>
>   ttl = 2;
>   appRec(s, ttl);
>   for (i=0; i<ttl ; i++)
>   {
>    cout << "\nStud ID : " << s[i].id;
>    cout << "\tName    : " << s[i].name;
>   }
>
> }
>
> void appRec(mystr *s1, int &ttl)
> {
>   ttl++;
>   cout << "\nTotal in function: " << ttl;
>   strcpy(s1[ttl].id, "1000005");
>   strcpy(s1[ttl].name, "Minotaic");
>   int i=0;
>   for (i=0; i<ttl; i++)
>   {
>    cout << "\nStud ID fnt : " << s1[i].id;
>    cout << "\tName    fnt : " << s1[i].name;
>   }
> }
>
>

"EL" <lameddie@yahoo.com> wrote in message news:a2um2g$1q1@imsp212.netvigator.com...
| Hi all,

Hi EL, some comments follow...

| I want to pass a structure to my own function and change its value, however
| i couldn't get the expected result. why?
|
| struct mystr
| {
| char id[7], name[21];

//  Here you are overwriting the memory you allocated.
//  id holds n-1 chars, but you parse it 'n' and leave no
//  room for the null terminator '\0'.
//  Making the storage const might also be better too.

| };
|
| void appRec(mystr* , int&);

//  You can avoid these pointers, see below...

| void main()

//  Should be int main(), as set by the standards association...

| {
|   mystr s[50];
|   int i, j, b, ttl;

//  You should always initialise all variables before you try to
//  access them, this will avoid undefined results in your code.
//  Providing some meaningfull names would not hurt at all either :-).

|   char vid[7], bid[7];
|
|   strcpy(s[0].id, "1000001");
|   strcpy(s[0].name, "RobertHi");
|   strcpy(s[1].id, "1000008");
|   strcpy(s[1].name, "KawaiiNic");

//  Loading records in this way is 'ok' for testing, but  would be
//  better to read in the records at run time, as you will see in my
//  example of your code below.

|   ttl = 2;

//  This magic number should be eliminated. Generally, you would
//  set this up to suit the number of records read in.

|   appRec(s, ttl);
|   for (i=0; i<ttl ; i++)

//  If your compiler supports it, it's a good idea to declare
//  your 'i' variable inside the for loop. For example:
    for ( int i = 0; i < ttl ;  i++ )

|   {
|    cout << "\nStud ID : " << s[i].id;
|    cout << "\tName    : " << s[i].name;
|   }
|
| }
|
| void appRec(mystr *s1, int &ttl)
| {
|   ttl++;

//  This is not right. The variable "ttl", comes in at the value '2',
//  so you have the records [0], [1] with data, and [2] which is empty
//  but waiting for some data to be entered, but you increment it
//  before adding any data to that index, so [2] is always empty.

|   cout << "\nTotal in function: " << ttl;
|   strcpy(s1[ttl].id, "1000005");
|   strcpy(s1[ttl].name, "Minotaic");
|   int i=0;
|   for (i=0; i<ttl; i++)
|   {
|    cout << "\nStud ID fnt : " << s1[i].id;
|    cout << "\tName    fnt : " << s1[i].name;
|   }
| }

//  I don't know why you have this loop in this function, but
//  your much better off, if you implement seperate functions
//  for seperate tasks. Please see below...

//  I have modified your existing code in such a way to give
//  you another perspective of achieving your goal. I hope you
//  can take something away from it :-).

# include <iostream>
  using namespace std; // Generic Declaration...

struct Person
 {
  static const int MAX = 50;
  char Id[MAX];
  char Name[MAX];
 };

void AddRecord(Person Rec[], size_t& Total)
 {
  size_t Count = 0;
  char Choice = ' ';

   do
     {
      cout << "Enter an id ";
      cin >> Rec[Count].Id;
      cout << "\nEnter person name ";
      cin.ignore();
      cin.getline(Rec[Count].Name, 50, '\n');

      cout << "Would you like to continue? [Y/N] ";
      cin >> Choice;
      Count ++;
      Total ++;
     }
   while( Choice != 'n' && Choice != 'N');
 }

void ShowRecords(Person Rec[], const size_t& Total)
 {
  cout << "\nRecords Stored In Database Are... ";
  for(size_t i = 0; i < Total; i++)
   {
    cout << "\nStudent ID " << Rec[i].Id;
    cout << "\tPerson Name " << Rec[i].Name;
   }
 }

int main()
 {
  const int NrRECORDS = 50;
  Person Record[NrRECORDS];
  size_t Total = 0;

  AddRecord( Record, Total );
  ShowRecords( Record, Total );

  return 0;
 }

Good Luck.
Chris Val