The pretest loop has the following format:
while
BooleanExpression do
statement;
|
The loop continues to execute until the Boolean expression becomes
FALSE. In the body of the loop, you must somehow affect the Boolean
expression by changing one of the variables used in it. Otherwise, an
infinite loop will result:
a := 5;
while a < 6 do
writeln (a);
|
Remedy this situation by changing the variable's value:
a := 5;
while a < 6 do
begin
writeln (a);
a := a + 1
end;
|
The WHILE ... DO lop is called a pretest loop because the
condition is tested before the body of the loop executes. So if the
condition starts out as FALSE, the body of the while loop never
executes.
