September 2017 Update

Task/Parsing-RPN-calculator-algorithm/Sinclair-ZX81-BASIC/parsing-rpn-calculator-algorithm.sinclair

@@ -0,0 +1,28 @@
+ 10 DIM S(5)
+ 20 LET P=1
+ 30 INPUT E$
+ 40 LET I=0
+ 50 LET I=I+1
+ 60 IF E$(I)=" " THEN GOTO 110
+ 70 IF I<LEN E$ THEN GOTO 50
+ 80 LET W$=E$
+ 90 GOSUB 150
+100 STOP
+110 LET W$=E$( TO I-1)
+120 LET E$=E$(I+1 TO )
+130 GOSUB 150
+140 GOTO 40
+150 IF W$="+" OR W$="-" OR W$="*" OR W$="/" OR W$="**" THEN GOTO 250
+160 LET S(P)=VAL W$
+170 LET P=P+1
+180 PRINT W$;
+190 PRINT ":";
+200 FOR I=P-1 TO 1 STEP -1
+210 PRINT " ";S(I);
+220 NEXT I
+230 PRINT
+240 RETURN
+250 IF W$="**" THEN LET S(P-2)=ABS S(P-2)
+260 LET S(P-2)=VAL (STR$ S(P-2)+W$+STR$ S(P-1))
+270 LET P=P-1
+280 GOTO 180