| 1 | PROGRAM POSTFIX(INPUT,OUTPUT); |
| 2 | |
| 3 | (* CONVERSION TO POSTFIX FORM *) |
| 4 | |
| 5 | VAR CH : CHAR; |
| 6 | |
| 7 | PROCEDURE FIND; |
| 8 | BEGIN REPEAT READ(CH) |
| 9 | UNTIL (CH<>" ") AND NOT EOLN |
| 10 | END; |
| 11 | |
| 12 | PROCEDURE EXPRESSION; |
| 13 | VAR OP : CHAR; |
| 14 | |
| 15 | PROCEDURE TERM; |
| 16 | |
| 17 | PROCEDURE FACTOR; |
| 18 | BEGIN IF CH="(" THEN |
| 19 | BEGIN FIND; EXPRESSION; (* CH = ) *) |
| 20 | END ELSE WRITE(CH); |
| 21 | FIND |
| 22 | END; (*FACTOR*) |
| 23 | |
| 24 | BEGIN FACTOR; |
| 25 | WHILE CH="*" DO |
| 26 | BEGIN FIND; FACTOR; WRITE("*") |
| 27 | END |
| 28 | END; (*TERM*) |
| 29 | |
| 30 | BEGIN TERM; |
| 31 | WHILE (CH="+")OR(CH="-") DO |
| 32 | BEGIN OP := CH; FIND; TERM; WRITE(OP) |
| 33 | END |
| 34 | END; (*EXPRESSION*) |
| 35 | |
| 36 | BEGIN FIND; |
| 37 | REPEAT WRITE(" "); |
| 38 | EXPRESSION; |
| 39 | WRITELN |
| 40 | UNTIL CH="." |
| 41 | END. |