Loops/Nested: Difference between revisions

end

</lang>

The use of GOTO, while convenient, is at odds with S-BASIC's structured programming ethos. Adding a boolean flag to the inner loop allows us to avoid the GOTO. Although S-BASIC has no explicit boolean variable type, integers, real numbers, characters, and strings can all be used as boolean variables. For integers, 0 is false and -1 is true. For real variables, 0 is false and any non-zero value is true. For characters, 'T', 't', 'Y', and 'y' are evaluated as true, while 'F', 'f', 'N', and 'n' are evaluated as false. Strings follow the same rule, with only the first character considered.

<lang BASIC>

$constant ROWS = 10

$constant COLUMNS = 10

$constant TOPVAL = 20

$constant TRUE = FFFFH

$constant FALSE = 0H

var i, j, done = integer

dim integer table(ROWS, COLUMNS)

rem - populate table using nested FOR..NEXT loops

for i=1 to ROWS

for j=1 to COLUMNS

table(i, j) = int(rnd(1) * TOPVAL) + 1

next j

next i

rem - show results using nested WHILE..DO loops

i = 1

done = FALSE

while i <= ROWS and not done do

begin

j = 1

while j <= COLUMNS and not done do

begin

print using "## "; table(i, j);

if table(i, j) = TOPVAL then done = TRUE

j = j + 1

end

print

i = i + 1

end

if i > ROWS then print "Target value of"; TOPVAL; " not found!"

The output is the same for both programs.