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Read or Readln question? looping?

Alright... I have an input file containing the following: (let's call it fiLe)

1001  John 30.0 0.0 0.0 0.0
-1

My pascal program contains:

PROGRAM sample;

VAR a:integer;
       b:string;
       c:real;
       d:real;
       e:real;

BEGIN
      reset(fiLe);
      write('reading...');
      read(fiLe, a, b, c,);  (* I have also tried readln here with the same result *)
END.

Here is the problem I have having.  If I read in just 'a' everything is fine.... it reads "1001"

BUT if I read in 'a' & 'b' ... I get the whole first line of my input file.  When I try to read 3 items from the input file, it tries to read after the end of line or end of file....

Ultimately, I want to have more than one line in the input file with the same format and have it quit reading when it hits a "-1" or "a"

Any help will be greatly appreciated.
     
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GunNam
Asked:
GunNam
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1 Solution
 
Wim ten BrinkSelf-employed developerCommented:
That's because reading a string means reading until the end of a line. The second value type you read is a string and thus it contains everything up until the last line.

It might be more useful to just use a temporary string, use ReadLn(AFile, TempStr) after declaring the var TempStr as a string and then split the string you've just read into the different variables you have. The functions Pos() and Val() will be very helpful with this.
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GunNamAuthor Commented:
If I were to read the whole line into a string, how would I go about getting the values I need out of it.  You mentioned Pos() and Val() but I'm still a bit confused.  
If it were in ANSI C, I could cast the string to an array and compare each array item to a space to get to the next item, but I'm not sure how this works in Pascal.

The real numbers in the input file could change in the amount of places it takes up so I can't bet on the positions always being the same.  
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GunNamAuthor Commented:
Ok... I just figured out that a string is actually an array and I can access each charactor with it's position in the array.  I'm gonna try and compare each array position to a " " and see if I can atleast get the first item... maybe a while will be better...
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GunNamAuthor Commented:
the compiler I am using does not support funtions supported by Turbo Pascal... is there a work around for getting stuff out of a string?  Since Pos() and Val() are out now?
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GunNamAuthor Commented:
I guess the question has now changed to:  How do I go about reading the input file:

1001  John 30.0 0.0 0.0 0.0
-1

where -1 is the sentinel and 6 items are of the type integer, string, real, real, real, real
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GunNamAuthor Commented:
I just thought of an idea, if someone would help me put it into code.
I could read the first "integer (first 4 digits)" with a regular read(number).

Then for the string, can't I read each character since I know that it will be the next 5 spaces after the space after the "number?"

Next, I'm assuming I could use the regular read command to get the following 4 floating point values...

What do you think?
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GunNamAuthor Commented:
would reading the file data into a record be a better approach?

I'm thinking read in the integer, then an array of chars then the REAL elements.
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GunNamAuthor Commented:
So you don't waste your time, I figured out how to read in 1 line.  I'm using a record and using an array of char for the STRING.  

If someone can help me with the sentinel problem, I will still award the full points.
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GunNamAuthor Commented:
I figured out the looping and reading in all the values.
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GunNamAuthor Commented:
Workshop_Alex, your comment about how the STRING reads propelled me to figure out how I could read in the rest of the values... thanks.
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Wim ten BrinkSelf-employed developerCommented:
Cool! Didn't have much time to checkup your problem but I see you managed it quite well by yourself! :-)
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