🚀 go-pugleaf

El writes:

> i'm using turbo c++ 3.0 for writing a very simple program, criteria as
> below:
>
> open a text file which formated as
> first 7 char is ID Number, Next 20 char is Name, Next 3 is marks 1, Next 3
> is marks 2.
> e.g    1002030ANDYLEUNG          100 95
>
> Now I want to open and read the file by using ifstream & ofstream, then
read
> the line
> which specify the length and put it into a defined structure like
>
> struct
> {
> char *id, *name
> int mark1, mark2
> }studrec
>
> however, i didn't know how to read the line with specific length of char
and
> how to loop it until end of file.

Here is a rough cut at it.

struct S
   {
    char id[8];   // pointers are pointless!  You *know* the size.
    char name[21];
    int mark1;
    int mark2;
    };
S s[100];  // space for 100 records
// Assume  a text file named in exists and is open.

int i = 0;
while(in)  // cast will return false at EOF
   {
    in.get(s[i].id, 7);
    in.get(s[i].name, 20);
    in >> s[i].mark1 >> s[i].mark2;
    in.get();  // discard '\n'  vulnerable to trailing blanks.
    i++;
   };

One hopes that that forms a base. After debuggging, of course.  No error
checking.

"osmium" <r124c4u2@mediaone.net> writes:

> > however, i didn't know how to read the line with specific length of char
> > and how to loop it until end of file.
> 
> Here is a rough cut at it.
> 
> struct S
>    {
>     char id[8];   // pointers are pointless!  You *know* the size.

Weeeeellll... ok, but it's not exactly very flexible.  Avoid magic
numbers where possible.


>     char name[21];
>     int mark1;
>     int mark2;
>     };
> S s[100];  // space for 100 records
> // Assume  a text file named in exists and is open.
> 
> int i = 0;
> while(in)  // cast will return false at EOF
>    {
>     in.get(s[i].id, 7);
>     in.get(s[i].name, 20);

In fact, these will return one character short each
time. istream::get() grabs n-1 characters, so you need:

  in.get( s[ i ].id, 8 );
  in.get( s[ i ].id, 21 );


>     in >> s[i].mark1 >> s[i].mark2;
>     in.get();  // discard '\n'  vulnerable to trailing blanks.
>     i++;
>    };

I'd be tempted to get the whole line as a string and process it from
there, probably safer.

-- 
Cheers,  // First time posting?  READ THIS:
Rich.    // http://snurse-l.org/acllc-c++/faq.html