User manual

mikroBasic PRO for dsPIC30/33 and PIC24
MikroElektronika
229
For Statement
The for statement implements an iterative loop and requires you to specify the number of iterations. The syntax of the
for statement is:
for counter = initial_value to nal_value [step step_value]
statement_list
next counter
counter is a variable which increments with each iteration of the loop. Before the rst iteration, counter is set to
initial_value and will increment until it reaches nal_value. nal_value will be recalculated each time the
loop is reentered.
This way number of loop iterations can be changed inside the loop by changing nal_value. With each iteration,
statement_list will be executed.
initial_value and nal_value should be expressions compatible with counter; statement_list may be
consisted of statements that don’t change the value of the counter.
Note that the parameter step_value may be negative, allowing you to create a countdown.
If nal_value is a complex expression whose value can not be calculated in compile time and number of loop
iterations is not to be changed inside the loop by the means of nal_value, it should be calculated outside the for
statement and result should be passed as for statement’s nal_value. statement_list is a list of statements that
do not change the value of counter.
Here is an example of calculating scalar product of two vectors, a and b, of length 10, using the for statement:
s = 0
for i = 0 to 9
s = s + a[i] * b[i]
next i
Endless Loop
The for statement results in an endless loop if nal_value equals or exceeds the range of the counter’s type.
While Statement
Use the while keyword to conditionally iterate a statement. The syntax of the while statement is:
while expression
statements
wend
statements are executed repeatedly as long as expression evaluates true. The test takes place before statements
are executed. Thus, if expression evaluates false on the rst pass, the loop does not execute.