Summing values from a loop

I am pretty new to Matlab, and this is a homework assignment I am struggleing with. We are supposed to create a script that will ask for a registration number repeatedly, then when you enter '9999999', it sums how many numbers are in each category. Here is the exact question:

Registration numbers for hot air balloons are strings of seven characters. The fifth character specifies balloon type: P, for propane filled; S, for solar heated; and H, for helium or hydrogen filled. The sixth character will identify the subtype: e, for helium and y, for hydrogen. The sixth character for types P and S should be x (no subtypes). We want to count the number of licenses of each type and subtype. The input will be given by the user and the string 9999999 will be used to indicate the end of the input. Write a MATLAB script to perform this counting. Create your own functions if needed. The interactive input/output should look like

Enter balloon registration number: "1322Px7"

Enter balloon registration number: "5721Hy6"

. . .

. . .

Enter balloon registration number: "9999999"

Propane filled balloons : 12

Solar heated balloons : 4

Helium filled balloons : 7

Hydrogen filled balloons : 3

My code asks for the registration number, and displays what it needs to, except that I can't seem to make it add the number of registration numbers in each category. I have no idea what to do, because my prof. never really covered this in class. Here is what I have so far:

clear
clc
condition = true;
while condition
    regNum = input('Enter balloon registration number: ', 's');
    if (length(regNum)>7 || length(regNum)<7)
        disp('Invalid registration number.')
        condition = false;
    else
        i = 1;
        if regNum(5)=='P' && regNum(6)=='x' % for P with x
            countPx = i;
            continue;
         elseif regNum(5)=='S' && regNum(6)=='x' % for S with x
             countSx = i;
             continue;
         elseif regNum(5)=='H' && regNum(6)=='y' % H with y
             countHy = i;
             continue;
         elseif regNum(5)=='H' && regNum(6)=='e' % H with e
             countHe = i;
             continue;
         elseif regNum == '9999999'
             totalPx = sum(countPx);
             totalSx = sum(countSx);
             totalHy = sum(countHy);
             totalHe = sum(countHe);
             matrix1 = [totalPx];
             matrix2 = [totalSx];
             matrix3 = [totalHy];
             matrix4 = [totalHe];
             pOutput = ['There are' matrix1 'propane balloons.'];
             disp(pOutput);
             sOutput = ['There are' matrix2 'solar heated balloons.'];
             disp(sOutput);
             hYOutput = ['There are' matrix3 'hydrogen balloons.'];
             disp(hYOutput)
             hEOutput = ['There are' matrix4 'helium balloons.'];
             disp(hEOutput)
             condition = false;
        else
            disp('Invalid registration number.')
            condition = false;
        end
        end
    end

Any ideas are greatly appreciated. Thanks in advance!

Answer 1

[David Hill]

function [P,S,He,Hy,RegList]= f()
condition = true;
count=1;
while condition
    regNum = input('Enter balloon registration number: ', 's');
    if length(regNum)>7 || length(regNum)<7
        disp('Invalid registration number.')
    elseif regNum=='9999999'
        condition=false;
    else
        RegList(count,:)=regNum;
        count=count+1;
    end
end
a=RegList(:,5);
b=RegList(:,6);
P=sum(a=='P');
S=sum(a=='S');
He=sum(a=='H'&b=='e');
Hy=sum(a=='H'&b=='y');
end

[AH]

This one is not working for me; it only returns the number of propane balloons, not the sums of the other types as well. Thanks anyway!

[David Hill]

Not sure what you are doing, but I have tried the solution and it works.

[AH]

I was able to fix it. With a few changes, I was able to get the desired output. Thank you!

[Benjamin Archibald]

Can you show me what changes you made? I am struggling with the same problem.

Thanks!