You can do one of two things. The first is use the PreviousValue() function to see if the current value equals the previous value, and if so then don't do the concatenation. The other option is to see if the last character in the string doesn't match the current value and then do the concatenation. use the same code in the previous post, but add a condtional statement before it.
option 1:
if {Sheet5_.Day} <> PreviousValue({Sheet5_.Day}) Then
str:=str+ {Sheet5_.Day};
option 2:
if Right(str,1) <> {Sheet5_.Day} then
str:=str+ {Sheet5_.Day};
I have all the Crystal syntax formulas and sample code for how to use them in three chapters of my Encyclopedia book. You can find out more about my books at Amazon.com or reading the Crystal Reports eBooks online.