Pascal insert user input to an array
I am trying to get better at functional programming. As a start I am planning on trying out with couple of languages like Pascal, Scheme, ML etc. First I started with Pascal. I am trying to insert user input into a integer array in pascal and then get them reverse.
1 program ReverseList;
2
3 var
4 i: Integer;
5 k: Integer;
6 a: array[1..100] of Integer;
7 begin
8 i := 0;
9 repeat
10 writeln('Enter a number');
11 readln(k);
12 if k > -1 then
13 i := i + 1;
14 a[i] := k;
15 until(k < 0);
16 for i := 1 to i do
17 writeln(a[i]);
18 end.
In past I have mostly been a java developer so I was so custom to using all the lists thats available. Also ideally I was wondering if I can build a list where I can iterate over the list based on the number of elements in that list.
It would be great if anyone could point me on the direction of g开发者_如何学编程ood tutorials in functional programming as well as syntax on above mentioned programming languages.
There are several problems with your program:
- The array is not initialized.
- There is no input checking, both i=0 and i>100 result in an illegal array index.
- The array index and the value are the same, is that correct?
- You only write the first 10 numbers (but you use a different index, which is certain to be out of range).
- The output is not in reverse.
There are also several pascal tutorials.
By the way, Pascal isn't a functional language. So if you really want to learn a functional language, you better try another one (like Lisp, Ml or probably F#).
It was a good practice and I managed to figure a solution for this. I am sure there are better ways to do, and also this doesn't look like I am using the functionalities of functional programming. But if anyone wants to provide a better solution please do so,
{author: Null-Hypothesis}
program ReverseList;
var
i: Integer; {integer to keep the array length}
k: Integer; {user input value}
a: array[1..100] of Integer; {array to store the user inputs}
begin
i := 0;
repeat {iterate until user input is negative or number of inputs exceed array size}
writeln('Enter a number or enter negative value to exit the program.');
readln(k);
if(k > -1) and (i < 100) then {check for negative value and size of the array}
begin
i := i + 1; {increase array index}
a[i] := k {assign value to array}
end
else
break; {exit if array size exceed the limit of array}
until(k < 0);
writeln;
{Printing the user input before the reversing the list}
writeln('Original order of the list');
for i := 1 to i do
writeln(a[i]);
writeln;
{Printing the reverse list}
writeln('Reversed List');
for i := i downto 1 do {decrement array index}
writeln(a[i]);
writeln('Bye!!!');
end.
Happy Coding, off to the next language...
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