Subsections

- Exercises

#
Printing multiples

We have already used `print` to convert plain values to characters displayed on your screen. In fact, `print` can be supplied with a row of values to be converted, so it is quite valid to write

       []INT i1 = (2,3,5,7,11,13);  print(i1)

You can also present an actual row-display. Instead of using

       print(2); print(blank); print(3)

you can write `print((2,blank,3))`. The doubled parentheses are necessary: the outer pair are needed by `print` anyway, and the inner pair are part of the row-display. Notice that the modes of the elements of the row-display are quite different. We shall learn in chapter 8 how that can be so.

Here is a program which will print the answers to the last exercise.

       PROGRAM test CONTEXT VOID
       USE standard
       BEGIN
        [,]INT i = ((1,-2,3,4),(-5,6,7,8));
        []REAL r= (1.4,0,-5.4,3.6);
        []CHAR s= "abcdefghijklmnopqrstuvwxyz"[@ ABS"a"];
        print(("i=",i,newline,
               "r=",r,newline,
               "s=[",s,"]",newline,
               "2 UPB i + UPB s[@1]=",
               2 UPB i+UPB s[@1],newline,
               "r[2:3]=",r[2:3],newline,
               "i[2,2] - r[3]=",
               i[2,2] - r[3],newline,
               "i[2,2:]=",i[2,2:],newline,
               "s[ABS""p"":ABS""t""]=",
               s[ABS"p":ABS"t"],
               newline))
       END
       FINISH

As you can see, `print` will quite happily take values of modes `[]CHAR`, `[,]INT`, `[]REAL` and so on4.3. Notice also that in order to get quote symbols in the last line to be printed, they are doubled. A common mistake is to omit a quote symbol or a closing comment symbol. If your editor provides lexical highlighting (usually called “syntax” highlighting), an omitted quote or comment symbol will cause a large part of your program to be highlighted as though it were a `[]CHAR` or a comment. The mistake will be very clear. If your editor does not support lexical highlighting, you will get an odd message from the compiler (usually to the effect that it has run out of program!).

## Exercises

3.9
  Write short programs to print the answers to all the exercises in this chapter from 3.2.1. You should insert multiples of `CHAR` at suitable points, as in the example above, so that you can identify the printed answers. Ans