Why is my code seemingly ignoring some of the for loop commands?

Hello, I'm new to MATLAB and I'm trying to create a user-defined function that acts like bin2dec using manual conversion of binary to decimal integer, but I can't figure out why I'm getting outputs of "1" or no output value for x altogether. Can someone please help me understand what's wrong with my code? Thank you!!

% mybin2dec takes one single valued text input argument representation of a binary number and converts it to a decimal integer
function b=mybin2dec(x)
x=input('Enter a binary number as a text input: ', 's')
str2num(x)
n=length(x)-1
for y=[1:length(x)]
    if x(y)==49
    d=(1*(2^n))
    n=n-1
    elseif x(y)==48
    d=(0*(2^n))
    n=n-1
    end
end
sum(d)

Answer 1

[Walter Roberson]

function b=mybin2dec(x)

You do not assign anything to b . Your code will error unless you do not assign the result of mybin2dec() to a variable and you supress the default output.

    d=(1*(2^n))

You overwrite all of d within each loop iteration. The final d that will be assigned is whatever it is assigned in the last iteration.

Hint:

    if x(y)==49

can be written as

    if x(y)=='1'

[Sydney]

Thank you so much for your help! Silly oversight on my part, it works now!

Answer 2

[Voss]

d is computed anew on each iteration of the for loop; thus after it's done the result you see is the last d that was computed, either 0 or 1. You should be adding each d to the sum of all the previous d's that were already calculated.

I see you have sum(d) at the end, but as d is a scalar, that doesn't really do anything. I guess that means that d is intended to be a vector the same length as x, in which case you should be storing d(y) instead of d inside the loop when you calculate it.

[Sydney]

Thank you very much! I appreciate your help!!

[Voss]

You're welcome!