Prog_2 course- 2014

2 bytes team

Kinan keshkeh

IT Engineering-Damascus University

3rd year

Files

TxT Files char(ACII)

Binary File 0/1

Who can tell me from where we read and

write in our normal program?

In Files:

Keyboard file

Screen file

Why files?

To save things..(whereas in normal way we cant save

things after program end)..

Then we can read|| write from it !

NOTE: First of all..

We have to know that each file has Pointer at

the Begin of file and Pointer at the End of it

-The end of line determined by (Enter) #13

There is : Physical name ( koko.txt /koko.bin)

logical name (f:txt / f:file of _sth_)

File : read

write

Note: Attention !! The most important thing

is the method we read and write files

modification has its arrangement(use

another file to help )

TXT FILES

The Definition

At main Program: Var f :Text;

At procedures/functions:

procedure ___(…Var f :txt)

We use “Assign” to link physical name with

logical name:

Assign(f,<filename>)

-If the file at (Bin)(the same folder of pascal) :

you don‟t have to write whole direction

Ex:(Assign(f,‟soso.txt‟) )

-else you have to write whole direction

Ex:(Assign(f ,‟D:\fifi\fofo\….\soso.txt‟) )

The Definition

At main Program: Var f :TXT;

At procedures/functions:

procedure ___(…Var f :txt)

We use “Assign” to link physical name with

logical name:

Assign(f,<filename>)

-If the file at (Bin)(the same folder of pascal) :

you don‟t have to write whole direction

Ex:(Assign(f,‟soso.txt‟) )

-else you have to write whole direction

Ex:(Assign(f ,‟D:\fifi\fofo\….\soso.txt‟) )

Read from Txtfile

Reset(f)

Read(f,c); (when you dunno how

the file is created )

Readln(f,st);

Readln(f); +1

close(f)

write from Txtfile

Rewrite(f)

write(f,c);

writeln(f,st);

writeln(f); +1

close(f)

Notes On Reset/Rewrite:

If File exist

If File Not exist

Reset Put the Pointer at the

begin of file ..

Error

Rewrite Erase file content

And put the Pointer at the

begin of file to write

Create new file

How can we know the end of file ??

How can we do the end of line ?

Eof(f): return true when

the file end.

Eoln (f): return true

when the line end.

Lets make it

real :D !!

-------- EMPno EMPName SAL

100 saeed 5000

2 Eyad 25000

78

-------- ------------

.

.

.

.

.

Ques: We want to write a Txt file like that below

..and read from it and print its content on Screen :

Write on file: Program Soso;

Var filename:string[20];

f:txt; i:integer; c:char; st:string[100];

Eno:integer; Ename:string[40]; Esal:real;

Begin

readln(filename); Assign(f, filename);

Rewrite(f);

writeln(f, „EMPno‟:15,‟EMPName‟:15,‟ SAL‟:20);

writeln(f,‟----------‟,‟ -----------------‟,‟-----------‟);

for i:=1 to 100 do

begin

readln(Eno,Ename,Esal);

writeln(f,Eno,Ename,Esal);

end;

close(f);

End.

Read form file 1) (because)/if we know the structure /how it is

written :

Reset(f);

Readln(f,st); Readln(f,st); While not eof(f) do

Begin

readln(f, Eno,Ename,Esal);

writeln(Eno,Ename,Esal);

end;

Close(f);

+1

2) (because)/if we don’t know the structure /how it

is written :

Reset(f);

While not eof(f) do

Begin

while not eoln(f) do

begin

read(f, c);

write(c);

end;

writeln; readln(f);

end;

Close(f);

Reset(f);

While not eof(f) do

Begin

while not eoln(f) do

begin

readln(f, st);

writeln(st);

end;

end;

Close(f);

Line long

You have to

define the

big number

string

Important Example

PC Computer

We have Txtfile In English( of course :p )

-Each word ends at its line.

-Between words there is Only one Space „ ‟.

There are in this file words “Computer” .. We want

replace them by ”PC”..

You have to Keep your

eyes with me all..

Program ComputerToPC;

VAR

f, new: text;

ch: Char;

s: string[8];

i: integer;

flag: boolean;

Begin

assign(f,'mo.txt');

reset(f);

assign(new,'new.txt');

rewrite(new);

while not eof(f) do

begin

flag := true;

while not eoln(f) do

begin

if flag then

read(f, s)

else

begin

read(f, ch);

s[8] := ch;

end;

if s = 'computer' then

begin

write(new, 'PC');

flag := true;

end

else

begin

flag := false;

if eoln(f) then

write(new, s)

else

write(new, s[1]);

for i := 1 to 7 do

s[i] := s[i+1];

end;

end;

readln(f);

writeln(new);

end;

close(new);

readln;

End.{program}

When we want to open an existing text file for writing at

the end of it , without removing its original contents

using the procedure Append

Appending to a text file:

Program Soso;

Var filename:string[20];

f:txt; st:string[10];

Begin

readln(filename); Assign(f, filename);

Append(f);

writeln(„put what do you want at the End of file : ‟);

readln(st);

writeln(f,st);

close(f);

End.

Homework:

you have a TXTfile it contains

Student name/student number/prog_1 mark/prog_2

mark/

1)put the sum of the two subjects to this file , then

ensure of that.

2)print the sum of the two subjects on

screen

+10 points

+7

+3

Group : group link

Mobile phone- Kinan : 0994385748

Facebook account : kinan’s account

2 bytes team