When evaluating a number for truth or falsehood, the computer assumes the number is true as long as its value isn't 0. When evaluating a comparison, it assigns a value of -I if the result is true, while false has a value of 0. In binary format, -1 is all 1's and 0 is all 0's. Therefore, when ANDing true/false evaluations, the result will be true if any bits in the result are true.

   50 IF X=7 AND W=3 THEN GOTO 10: REM ONLY TRUE IF BOTH X=7
      AND W=3 ARE TRUE
   60 IF A AND Q=7 THEN GOTO 10: REM TRUE IF A IS NON-ZERO
      AND Q=7 IS TRUE

ASC

Action: ASC will return a number from 0 to 255 which corresponds to the Commodore ASCII value of the first character in the string. The table of Commodore ASCII values is shown in Appendix C.

   10 PRINT ASC("Z")
   20 X = ASC("ZEBRA")
   30 J = ASC(J$)

If there are no characters in the string, an ?ILLEGAL QUANTITY error results. In the third example above, if J$="", the ASC function will not work. The GET and GET# statement read a CHR$(0) as a null string. To eliminate this problem, you should add a CHR$(0) to the end of the string as shown below.

   30 J = ASC(J$ + CHR$(0))