BBC BASIC Programmers' Reference

by Richard Russell, August 2011

If you want to substitute one character for another in a string (for example you want to change every colon ':' into a dash '-') there's a more efficient and elegant way than looping through each character in turn:

        REPEAT
          i% = INSTR(A$,":")
          IF i% MID$(A$,i%,1) = "-"
        UNTIL i%=0

This is particularly efficient in the typical case when not many characters need to be substituted.