To exchange the values of two variables.
SWAP variable1,variable2
Any type variable may be swapped (integer, single-precision, double-precision, string), but the two variables must be of the same type or a "Type mismatch" error results.
LIST 10 A$="ONE ": B$="ALL ": C$="FOR " 20 PRINT A$ C$ B$ 30 SWAP A$, B$ 40 PRINT A$ C$ B$ RUN ONE FOR ALL ALL FOR ONE
Line 30 swaps the values in the A$ and B$ strings.