How to find the biggest number from a txt file? - pascal

Question

I have to find out the biggest number from a txt file. Numbers are for example:
9 8 7 6 5
Someone told me, that it should works, but it didn't, and I have no clue how to work with file bcs.
program file;
uses crt;
var i,count,help:integer;
numb:array [1..9] of integer;
f:text;
begin
clrscr;
assign(f,'file1.txt');
reset(f);
readln(f,count);
for i:=1 to count do
readln(f,numb[i]);
close(f);
for i:=2 to count do
begin
if (numb[i-1] < numb[i]) then
help:=numb[i-1];
numb[i-1]:=numb[i];
numb[i]:=help;
end;
for i:=1 to count do
begin
write(numb[i]);
end;
readln;
end.

Answer 1

If you only want to know the highest number, you can use a running maximum while reading the numbers in the file.
As a user you don't have to know how many numbers there are in the file. The program should determine that.
I wrote a little test file, called file1.txt:
9 8 7 6 3 11 17
32 11 13 19 64 11 19 22
38 6 21 0 37
And I only read the numbers, comparing them with Max. That is all you need.
No need to read the data into an array and
no need to (try to) sort the data. You only want the highest number, right?
And there is also no need for the user to know or enter the number of numbers in the text file.
program ReadMaxNumber;
uses
Crt;
var
Max, Num: Integer;
F: Text;
begin
ClrScr;
Assign(F, 'file1.txt');
Reset(F);
Max := -1;
while not Eof(F) do
begin
Read(F, Num);
if Num > Max then
Max := Num;
end;
Close(F);
Writeln('Maximum = ', Max);
Readln;
end.
When I run this, the output is as expected:
Maximum = 64

Answer 2

There are a few mistakes in the code provided:
The program name is file. The program name cannot be a keyword;
You read from the file the variable count, but the actual value cannot be found in the file, so count=0. For this reason, the for loop which reads the data from the file is never executed. You either read it from a file or from the keyboard (in the solution below, I chose the second option);
You use readln when you read from the file. readln moves the cursor on the next line after it reads the data. This means that only the first number, 9, is stored into numb. Replace readln with read;
At the second for loop, you say that if ... then. If you want all the three instructions to be executed (and I think you do, because it's an exchange of values), put them between begin and end. Otherwise, only the first instruction is executed if the condition is true, the others are always been executed;
The method to determine the maximum is an overkill. Better if you take a variable, max, which initially gets the value of the first element in the array, then you cycle in the remaining values to see if a value is higher than max.
The final code looks like this:
program file1;
uses crt;
var i,count,help, max:integer;
numb:array [1..9] of integer;
f:text;
begin
clrscr;
assign(f,'file1.txt');
reset(f);
writeln('Please input a number for count :');
readln(count);
for i:=1 to count do
read(f,numb[i]);
close(f);
max:=numb[1];
for i:=2 to count do
if numb[i]>max then
max:=numb[i];
write('The result is: ',max);
readln;
end.