Send help for the world's easiest matlab code and for some reason I can't get it to work

   function i = find_first(array, value)
     % FIND_FIRST Find first index of a value in an array.
     % I = FIND_FIRST(ARRAY, VALUE) returns the index I into the ARRAY where the
     % first occurrence of VALUE is found. If VALUE is not in ARRAY, then an
     % error is raised.
     n = length(array);
     i = 1;
     while ??? && ???
         i = i + 1;
  end
     %Check if value was not found
     if ???
         error('VALUE was not found.');
  end

I can't do it. What are the question marks supposed to be?

[Muhammed Ahkbar]

>> find_first([2,7,1,8,2,8,1], 8)

This is an example question for the function

Answer 1

[Walter Roberson]

while your index is not past the end of the vector and the current value is not the match you are looking for

if your index is past the end of the vector

[Muhammed Ahkbar]

And how would i write that as code?

[Walter Roberson]

What is your index variable? Where is the end of the vector? How could you compare one particular vector item to the target?

[mitch midalia]

function i = find_first1(array, value)
% FIND_FIRST Find first index of a value in an array.
% I = FIND_FIRST(ARRAY, VALUE) returns the index I into the ARRAY where the
% first occurrence of VALUE is found. If VALUE is not in ARRAY, then an
% error is raised.
n = length(array);
i = 1;
while array(i)<=array(n) && array(i)~=value   
i = i + 1;
en

   function i = find_first1(array, value)
  % FIND_FIRST Find first index of a value in an array.
  % I = FIND_FIRST(ARRAY, VALUE) returns the index I into the ARRAY where the
  % first occurrence of VALUE is found. If VALUE is not in ARRAY, then an
  % error is raised.
  n = length(array);
  i = 1;
  while array(i)<=array(n) && array(i)~=value   
  i = i + 1;
  end

I can't figure out why i isn't changing. pls help

[Muhammed Ahkbar]

Solved it and this is the function i obtained

function i = find_first(array, value)
   % FIND_FIRST Find first index of a value in an array.
   % I = FIND_FIRST(ARRAY, VALUE) returns the index I into the ARRAY where the
   % first occurrence of VALUE is found. If VALUE is not in ARRAY, then an
   % error is raised.
   n = length(array);
   i = 1;
   while (array(i) - value) <= array(n) && value ~= array(i)
       i = i + 1;
   end
   %Check if value was not found
   if value ~= array
       error ('Value was not found');
   end

[mitch midalia]

Thank you very much, but I still don't understand why my function earlier wasnt working. Could you please explain? Thanks :)

[Walter Roberson]

i <= n & array(i) ~= value