Extracting all characters of a postcode before the space

Question

I am trying to extract the first characters from a postcode into a separate field that can then be used as a parameter.  If i search on postcodes starting with (for example) M1, this is bring out not only M1 but also M11, M12, etc.
I have found a While Constructs formula example in my training book that extracts the Surname from a field containing the FirstName and Surname.  I have recreated this and applied to my postcode field but it is bring out the characters AFTER the space in the postcode and not the characters BEFORE.
Does anybody know how to reverse the following so that it extracts the characters BEFORE the space?
stringVar PCode := {ADDRESS.POSTCODE};
numberVar i:=1;
numberVar Strlen := length (PCode);
numberVar Result:= -1;
while i <= Strlen and Result= -1 do
    stringVar Position:= Mid (PCode,i,1);
    if Position = " " then
        Result:= i;
        i:= i + 1;
stringVar PostSearch := mid (PCode, Result+1, (Strlen-Result));
PostSearch

Answer 1

Hello Tracy,
I am not sure how to help you on this however I have found an interesting code from one of the forums, see if that makes your life any better.
Here's the code to extract the zip. what i did is checked for a number in the string, once i found it i checked
for next 4 character if they are number (as zipcode is 5 digits). if all 5 character are number then i m assiging
it to a variable and coming out of loop otherwise i m going for next charachter.
creat two formulas
1st formula name is  "zipcode" which has following code
shared numbervar strlen := length({table.fieldname});
shared stringvar zipcode := "";
shared numbervar i := 0;
shared numbervar a := 0;
shared numbervar b := 0;
shared numbervar c := 0;
shared numbervar z  := 0;
for i := 1 to strlen do
if mid({table.fieldname},i,1) in ["0","1","2","3","4","5","6","7","8","9"] then
     a := i;
     b := i;
     c :=  i + 4;
     z  := 0;
     zipcode := "";
    for a := b to c do
    ( if mid({table.fieldname},a,1) in ["0","1","2","3","4","5","6","7","8","9"] then
         (z := z + 1;
          zipcode := zipcode &mid({table.fieldname},a,1);
          if z = 5 then
          i := i+strlen+1;
          zipcode)
     else
           zipcode;
2. the 2nd formula is  "zip" which has folllowing code
     shared stringvar zipcode;
now keep  both  the formula in the report and supress zipcode.
You will get the zipcode
As I said this is not mine, I took it from somewhere else however the way he did it, makes more sense.
Let us know if this works.
Regards
Jehanzeb