Bronze Edition Guide - True BASIC

8. Loop Structures 51
This program prints a pattern of x’s on the screen:
x
xx
xxx
xxxx
xxxxx
xxxxxx
Let’s analyze this program. It has two loops: an outer loop with the variable row as the
loop index, and within that an inner loop with the index variable xcount.
———————————————————————————————————————
x The inner or nested loop must be entirely inside the outer loop.
———————————————————————————————————————
Each time the outer loop goes through one big cycle, the inner loop goes through as many
cycles as the current value of row. This creates the triangle pattern. As you can see, the
first row has one x, the second has two, and so on.
Note the empty PRINT statement just after the inner loop and just before the end of the
outer loop. This second PRINT statement is carried out only at the end of a row. It tells
True BASIC to start a new line. If it wasn’t there, the program would just print 21 x’s on
one line.
If you want to print more than one triangle, you’ll have to use three loops, not just two. Nest
a new loop between the row and xcount loops. Notice how the indenting and blank lines
help you keep track of which loop is which:
! Print pattern of x’s.
!
FOR row = 1 to 6
FOR triangle = 1 to 3
! new loop starts here
FOR xcount = 1 to row
PRINT “x”;
NEXT xcount
PRINT,
NEXT triangle
! new PRINT with comma
! new loop ends here
PRINT
NEXT row
END