Computer Science Canada

Substring index greater than string length
Author:  cat8864 [ Mon Nov 24, 2008 7:02 pm ]
Post subject:  Substring index greater than string length
Why do I keep getting "Substring index is greater than length of string" when I have more than one character in my input?

Turing:

var sentence := ""
var a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z := 0

put "Please enter a sentence"
get sentence : *
put " "

var size := length (sentence)
for I : 1 .. size
    if index (sentence, "a" (I)) > 0 or index (sentence, "A" (I)) > 0 then
        a := a + 1
    elsif index (sentence, "b" (I)) > 0 or index (sentence, "B" (I)) > 0 then
        b := b + 1
    elsif index (sentence, "c" (I)) > 0 or index (sentence, "C" (I)) > 0 then
        c := c + 1
    elsif index (sentence, "d" (I)) > 0 or index (sentence, "D" (I)) > 0 then
        d := d + 1
    end if
end for
put "Here are the totals for each letter"
put "A = ", a
put "B = ", b
put "C = ", c
put "D = ", d
Author:  drij [ Mon Nov 24, 2008 7:30 pm ]
Post subject:  Re: Substring index greater than string length
You have the string index on the wrong strings. It should look like this:
Turing:
if index (sentence (I), "a") > 0 or index (sentence (I), "A") > 0 then


EDIT: You don't actually have any need for the index function. It is much simpler and efficient to do the following:
Turing:
if sentence (I) = "a" or sentence (I) = "A" then
Author:  [Gandalf] [ Mon Nov 24, 2008 7:36 pm ]
Post subject:  RE:Substring index greater than string length
code:
"a" (I)

What does this evaluate to for different values of I?
Try it out:
code:
for i: 1 .. 3
    put i,  " ", "a"(i)
Author:  cat8864 [ Mon Nov 24, 2008 8:10 pm ]
Post subject:  RE:Substring index greater than string length
Thanks
Author:  andrew. [ Mon Nov 24, 2008 8:15 pm ]
Post subject:  RE:Substring index greater than string length
Why did you make all the variables a to z? You could've made an array like this:
code:
var letters : array 1..26 of int %This is basically 26 integers all under the same variable name, plus a number.

for i : 1..26 %This loop is to make all the letters equal 0
    letters (i) := 0
end for


This is better because there is less code and also you can keep track of everything right in one variable. So let's say your sentence has 3 a's and 4 d's. Well you would add 3 to letters(1), because we are making 1=A, 2=B, etc. You would also add 4 to letters(4) because that is D. If you don't understand this and want to learn about it, check out the Turing Walkthrough in the Tutorials section. It explains arrays there perfectly.
Author:  cat8864 [ Mon Nov 24, 2008 9:28 pm ]
Post subject:  RE:Substring index greater than string length
ya, I realized the length of the code was a bit of a problem so I changed it to ASCII characters in two for loops. Still needed to use the same letter selection though. Thanks everybody

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