Computer Science Canada

Help for if statements
Author:  storm2713687 [ Wed Feb 27, 2013 1:43 pm ]
Post subject:  Help for if statements
I was just wondering if I can use if statements like this (For an example):
Turing:


var operation : int
put "Type and enter 1 for operation 1, 2 for operation 2, or 3 for operation 3."
get operation
if 1 then
    put "1+1=", 1 + 1
elsif 2 then
    put "1+2=", 1 + 2
else
    put "1+3=", 1 + 3
end if



Would that work? I've only used booleans for my if statements so far, but I'd like to try this, but I'm not sure if it works (last time I remember doing something like that, it failed).
Author:  Tony [ Wed Feb 27, 2013 5:28 pm ]
Post subject:  RE:Help for if statements
you could read the documentation -- if -- to see exactly what you can do with the statement.
Author:  Insectoid [ Wed Feb 27, 2013 7:39 pm ]
Post subject:  RE:Help for if statements
The nice thing about programming is that if you want to try something, you can.
Author:  storm2713687 [ Thu Feb 28, 2013 8:31 pm ]
Post subject:  Re: RE:Help for if statements
Insectoid @ Wed Feb 27, 2013 7:39 pm wrote:
The nice thing about programming is that if you want to try something, you can.

I was at school so I couldn't use Turing xD
Since there's compsci at high schools, the computer probably had it, but I just didn't know the location of it. Thanks for helping though, guys!
Author:  jbking [ Fri Mar 01, 2013 12:30 pm ]
Post subject:  Re: Help for if statements
Case would be like what you want so there is a command to do that, if you want to know about it.[/url]
Author:  yazdmich [ Fri Mar 01, 2013 12:55 pm ]
Post subject:  Re: Help for if statements
Turing:


var op : int
put "Type and enter 1 for operation 1, 2 for operation 2, or 3 for operation 3."
get op
if op = 1 then
    put "1+1=", 1 + 1
elsif op = 2 then
    put "1+2=", 1 + 2
else
    put "1+3=", 1 + 3
end if


You must tell the compiler what variable to read, easy mistake, Turing's compiler is highly declarative. almost nothing is inferred (constant typing [int, real, nat, string etc] can be inferred, but everything else is declared)
Author:  storm2713687 [ Fri Mar 01, 2013 5:11 pm ]
Post subject:  Re: Help for if statements
Jbking, what do you mean by that?
yazdmich @ Fri Mar 01, 2013 12:55 pm wrote:
Turing:


var op : int
put "Type and enter 1 for operation 1, 2 for operation 2, or 3 for operation 3."
get op
if op = 1 then
    put "1+1=", 1 + 1
elsif op = 2 then
    put "1+2=", 1 + 2
else
    put "1+3=", 1 + 3
end if


You must tell the compiler what variable to read, easy mistake, Turing's compiler is highly declarative. almost nothing is inferred (constant typing [int, real, nat, string etc] can be inferred, but everything else is declared)

Can you give an example plz? Smile
I don't quite understand that Sad
Author:  yazdmich [ Fri Mar 01, 2013 5:39 pm ]
Post subject:  Re: Help for if statements
storm2713687 @ Fri Mar 01, 2013 5:11 pm wrote:
Jbking, what do you mean by that?
yazdmich @ Fri Mar 01, 2013 12:55 pm wrote:
Turing:


var op : int
put "Type and enter 1 for operation 1, 2 for operation 2, or 3 for operation 3."
get op
if op = 1 then
    put "1+1=", 1 + 1
elsif op = 2 then
    put "1+2=", 1 + 2
else
    put "1+3=", 1 + 3
end if


You must tell the compiler what variable to read, easy mistake, Turing's compiler is highly declarative. almost nothing is inferred (constant typing [int, real, nat, string etc] can be inferred, but everything else is declared)

Can you give an example plz? Smile
I don't quite understand that Sad


I fixed your code so it would work in turing. declaring means to say what it is checking, in this case the value of the variable op
Author:  jbking [ Fri Mar 01, 2013 6:17 pm ]
Post subject:  Re: Help for if statements
I mean that the structure of code you want where you just want to state the value and have it automatically do the line you want already exists as a separate command called "case" which you may want to research. From the documentation that should look a lot like what you wanted to some degree if I interpret what you wanted correctly. Here would be an example that is similar to what you wanted:

Turing:

        case mark of
            label 9, 10 :   put "Excellent"
            label 7, 8 :        put "Good"
            label 6 :       put "Fair"
            label :     put "Poor"
        end case
Author:  storm2713687 [ Fri Mar 01, 2013 7:38 pm ]
Post subject:  Re: Help for if statements
yazdmich @ Fri Mar 01, 2013 5:39 pm wrote:
storm2713687 @ Fri Mar 01, 2013 5:11 pm wrote:
Jbking, what do you mean by that?
yazdmich @ Fri Mar 01, 2013 12:55 pm wrote:
Turing:


var op : int
put "Type and enter 1 for operation 1, 2 for operation 2, or 3 for operation 3."
get op
if op = 1 then
    put "1+1=", 1 + 1
elsif op = 2 then
    put "1+2=", 1 + 2
else
    put "1+3=", 1 + 3
end if


You must tell the compiler what variable to read, easy mistake, Turing's compiler is highly declarative. almost nothing is inferred (constant typing [int, real, nat, string etc] can be inferred, but everything else is declared)

Can you give an example plz? Smile
I don't quite understand that Sad


I fixed your code so it would work in turing. declaring means to say what it is checking, in this case the value of the variable op

Ohhh thanks Razz
Is it possible to change else to elsif op = 3?

jbking @ Fri Mar 01, 2013 6:17 pm wrote:
I mean that the structure of code you want where you just want to state the value and have it automatically do the line you want already exists as a separate command called "case" which you may want to research. From the documentation that should look a lot like what you wanted to some degree if I interpret what you wanted correctly. Here would be an example that is similar to what you wanted:

Turing:

        case mark of
            label 9, 10 :   put "Excellent"
            label 7, 8 :        put "Good"
            label 6 :       put "Fair"
            label :     put "Poor"
        end case

I didn't get there in turing yet xD
Thanks for helping though Smile
Author:  Raknarg [ Sat Mar 02, 2013 1:11 pm ]
Post subject:  RE:Help for if statements
Personally I wouldn't use cases in turing, they're stupid. In most languages you can set ranges, but not in Turing. With bigger ranges you might as well use ifs.
Author:  storm2713687 [ Sat Mar 02, 2013 7:51 pm ]
Post subject:  Re: RE:Help for if statements
Raknarg @ Sat Mar 02, 2013 1:11 pm wrote:
Personally I wouldn't use cases in turing, they're stupid. In most languages you can set ranges, but not in Turing. With bigger ranges you might as well use ifs.


Well now I know another thing not to use in turing Razz


Btw, is it possible to have the if statement something like this:
if variable1 = yes then
put "hi"
elsif variable1 = no then
put "bye"
end if
Author:  Raknarg [ Sat Mar 02, 2013 7:56 pm ]
Post subject:  RE:Help for if statements
Why not? It's essentially the same as what you were doing before.
Author:  storm2713687 [ Sat Mar 02, 2013 9:25 pm ]
Post subject:  Re: RE:Help for if statements
Raknarg @ Sat Mar 02, 2013 7:56 pm wrote:
Why not? It's essentially the same as what you were doing before.

Well, I just wanted to have a bigger variety of options for my if statements.
Now I have another question Razz
Can I use an if statement within another if statement?
Author:  Tony [ Sat Mar 02, 2013 9:36 pm ]
Post subject:  Re: RE:Help for if statements
storm2713687 @ Sat Mar 02, 2013 9:25 pm wrote:

Can I use an if statement within another if statement?

Yes. As I've linked to above ? http://compsci.ca/holtsoft/doc/if.html "An ifStatement is:"
Quote:

if trueFalseExpn then
statementsAndDeclarations
{ elsif trueFalseExpn then
statementsAndDeclarations }
[ else
statementsAndDeclarations ]
end if

So inside of an ifStatement you can have any statementsAndDeclarations, which includes other ifStatement.
Author:  storm2713687 [ Sat Mar 02, 2013 9:42 pm ]
Post subject:  Re: RE:Help for if statements
Tony @ Sat Mar 02, 2013 9:36 pm wrote:
storm2713687 @ Sat Mar 02, 2013 9:25 pm wrote:

Can I use an if statement within another if statement?

Yes. As I've linked to above ? http://compsci.ca/holtsoft/doc/if.html "An ifStatement is:"
Quote:

if trueFalseExpn then
statementsAndDeclarations
{ elsif trueFalseExpn then
statementsAndDeclarations }
[ else
statementsAndDeclarations ]
end if

So inside of an ifStatement you can have any statementsAndDeclarations, which includes other ifStatement.


Oh whoops, idk what happended with me at that time... idk why I didn't look at it lol. Thanks though, that answers a hell lot Razz
Author:  Raknarg [ Sat Mar 02, 2013 10:02 pm ]
Post subject:  RE:Help for if statements
It's called nesting, which you can do with basically any structure. A loop within a loop, if within an if, for within a for, and such.
Author:  storm2713687 [ Sat Mar 02, 2013 10:06 pm ]
Post subject:  Re: RE:Help for if statements
Raknarg @ Sat Mar 02, 2013 10:02 pm wrote:
It's called nesting, which you can do with basically any structure. A loop within a loop, if within an if, for within a for, and such.


Do I have to add a certain code to my program or will it work if I just use an if within an if?
Author:  Raknarg [ Sat Mar 02, 2013 10:12 pm ]
Post subject:  Re: Help for if statements
Turing:

var x : int := 14

if x mod 2 = 0 then
     if x >= 10 then
          put "This is an even number greater or equal to ten."
     else
          put "This is an even number less than ten."
     end if
else
     if x > 10 then
          put "This is an odd number greater than ten."
     else
          put "This is an odd number less than ten."
     end if
end if


try running that.
Author:  storm2713687 [ Sun Mar 03, 2013 8:39 pm ]
Post subject:  Re: Help for if statements
Raknarg @ Sat Mar 02, 2013 10:12 pm wrote:
Turing:

var x : int := 14

if x mod 2 = 0 then
     if x >= 10 then
          put "This is an even number greater or equal to ten."
     else
          put "This is an even number less than ten."
     end if
else
     if x > 10 then
          put "This is an odd number greater than ten."
     else
          put "This is an odd number less than ten."
     end if
end if


try running that.


Thanks for helping, but what does mod do after the "if" statement at the top? Sorry, I'm so bad at this Razz
Author:  Dreadnought [ Sun Mar 03, 2013 9:12 pm ]
Post subject:  Re: Help for if statements
It's just a positive remainder from integer division. Basically, "x mod 2" will return 1 if x is an odd number and 0 if x is an even number.
Author:  Raknarg [ Mon Mar 04, 2013 12:46 pm ]
Post subject:  RE:Help for if statements
Or if I was looking at an angle, for instance, and wanted to have it only between 0 and 359. Then lets say I had an angle of 450.

450 mod 360 = 90

Divides the left number by the right one, then returns whatever the remainder is.
Author:  storm2713687 [ Mon Mar 04, 2013 8:12 pm ]
Post subject:  Re: Help for if statements
I'm confused Sad
So is mod supposed to be division?
Author:  Insectoid [ Mon Mar 04, 2013 8:21 pm ]
Post subject:  RE:Help for if statements
Mod returns the remainder of a division. 10/3 = 3, with a remainder of 1. 10 mod 3 = 1.

The way to check if a number is odd or even is to divide it by 2 and take the remainder. If the remainder is 0, then it's even. If the remainder is 1, then it's even. 5/2 = 2, with a remainder of 1. 5 mod 2 = 1, therefor 5 is odd. 4/2 = 2, with a remainder of 0. 4 mod 2 = 0.
Author:  storm2713687 [ Tue Mar 05, 2013 11:49 am ]
Post subject:  Re: RE:Help for if statements
Insectoid @ Mon Mar 04, 2013 8:21 pm wrote:
Mod returns the remainder of a division. 10/3 = 3, with a remainder of 1. 10 mod 3 = 1.

The way to check if a number is odd or even is to divide it by 2 and take the remainder. If the remainder is 0, then it's even. If the remainder is 1, then it's even. 5/2 = 2, with a remainder of 1. 5 mod 2 = 1, therefor 5 is odd. 4/2 = 2, with a remainder of 0. 4 mod 2 = 0.

I still don't really get it... isn't 10/3 supposed to be like 3.something?
Author:  DemonWasp [ Tue Mar 05, 2013 1:22 pm ]
Post subject:  RE:Help for if statements
If you divide 10 solid objects (each indivisible) into 3 even piles, then each pile has 3 objects in it and you have one left over (the remainder).

10 div 3 will give you 3, the number of objects in each pile.
10 mod 3 will give you 1, the number of objects left over.
Author:  storm2713687 [ Tue Mar 05, 2013 1:24 pm ]
Post subject:  Re: RE:Help for if statements
DemonWasp @ Tue Mar 05, 2013 1:22 pm wrote:
If you divide 10 solid objects (each indivisible) into 3 even piles, then each pile has 3 objects in it and you have one left over (the remainder).

10 div 3 will give you 3, the number of objects in each pile.
10 mod 3 will give you 1, the number of objects left over.


Ohhh I get it now, thanks Razz
Is mod supposed to be some kinda simple math thing?
Author:  DemonWasp [ Tue Mar 05, 2013 2:11 pm ]
Post subject:  RE:Help for if statements
mod stands for "modulus", which basically means "divide evenly and find the remainder".

This leads to a kind of mathematics called "modular arithmetic". It sounds scary, but the hours in a day follow the same basic rules: hours start at 1, count up to 12, then return to 1 again. But! The next number after 12 is 13, and 13 mod 12 = 1. And, the hour after that, hour #14, is normally called "2pm", but notice that 14 mod 12 = 2. For more detail, see http://en.wikipedia.org/wiki/Modular_arithmetic . There's a discussion of modular arithmetic in a first-year university class, usually called "Classical Algebra" or similar.

Note: Hours don't follow exactly the same system, because 12 mod 12 = 0 (you can divide 12 objects into 12 even piles with 0 left over). However, the idea is the same, just offset by one. The hour "12am midnight" can be thought of as 0, and the hour "1am" thought of as 1. Then "11am" is 11, and "12pm noon" is 0 (because 12 mod 12 = 0).

Note: Negative numbers may not behave as you expect with mod. For details, see the div mod and rem commands:
http://compsci.ca/holtsoft/doc/div.html
http://compsci.ca/holtsoft/doc/mod.html
http://compsci.ca/holtsoft/doc/rem.html
Author:  Raknarg [ Tue Mar 05, 2013 4:56 pm ]
Post subject:  RE:Help for if statements
For instance, you can try this:

put -450 rem 360
put -450 mod 360

Notice how the first one results -90 and the second results 270.

:


You can syndicate this boards posts using the file backend.php or view the topic map using sitemap.php.

Terms of Use | Privacy Policy