In programming, a common task is to swap the values of two variables. Lines 40-60 of the program below perform the swap using a temporary variable (T).

10 A=123
20 B=456
30 PRINT A,B
40 T=A
50 A=B
60 B=T
70 PRINT A,B

Rewrite the program to swap the values in A and B without using a temporary variable.

Note: The new program will not require sophisticated programming or complex math.

Is XOR math? Here is a "solution" with absolutely no math:

10 A=123
20 B=456
30 PRINT A,B
70 PRINT B,A

It does the same thing as the original program as far as an external observer is concerned!

Posted by Richard on 2004-01-02 21:51:47