repetition structure - a loop - write code once put it in a structure that repeats as many times as necessary
condition controlled loop - while loop - uses a true false condition
while loop (pre-test loop) condition controlled loop - uses a true false condition
- condition tests for T or F
- a statement that is repeated as long as the condition is true
- condition is tested BEFORE performing an iteration
- it will NEVER execute if condition is false
for loop count controlled loop - a loop that repeats a specific number of times - designed to work with a sequence of data items.
for variable in [val1, val2, val3]:
print(variable)
iteration - each execution of the body of the loop
target variable - the target of an assignment at the beginning of each iteration
for num in range(5):
print(num)
for x in range(5):
print('Hello World')
range(1,5) - 1 is the start value, 5 is the ending limit - prints 1 2 3 4
step value - if you add a 3rd argument to a range function it will increment that number of times
for num in range(1, 10, 2):
print num
returns >> 1,3,5,7,9
accumulator - the variable used to keep the running total
running total - sum of numbers that accumulates with each iteration of the loop
- a loop that reads each number in the series
- a variable that accumulates the total of the numbers as they are read
augmented assignment operator += , -=, *=, %= (total = total + number) == total += number
sentinel value - a special value that marks the end of a sequence of values(you choose it and make it unique enough not to be confusing)
validation loop (error trap) (error handler)
- input is read
- loop is executed
- if input data is bad the loop executes its block of statements
- loop displays an error message to user
input validation - if input is invalid the program discards it and prompts user for the correct data
priming read - get users input and send it to the validation loop as a condition to be t or f If true run the program. If false prompt user for the correct data
nested loop - loop inside another loop
- an inner loop goes through all of its iterations for every iteration of an outer loop
- inner loops complete their iterations faster than outer loops
- to get the total number of iteration of a nested loop - multiply the number of iteration of all the loops