Lecture 27

for Loop

Why use for loops?:

more expressive, succinct, and compact when expressing loops that execute a known number of iterations
for loops convey more intent than while loops that execute a known number of iterations

How to use for loops?:

any variable used in expression1, expression2, or expression3 will need to be previously declared
expression1 is used to initialize some parameter, typically called an index
expression2 is a condition that must be true for the loop to continue execution
expression3 is is used to alter the value of the parameter initially assigned by expression1

Comparing for loop with while loop:

This program compares using a for loop with using a while loop

both blocks of code do the same thing
for loop is more compact vertically
for loop is more concise and all relevant statements are located in one place
while loop is more compact horizontally
for loop is better for loops with a known number of iterations
while loop is better for loops with an unknown number of iterations
- unknown_iterations.c:

Why use do while loops?:

do while loops convey more intent than while loops when the code should be executed once before the condition is checked

How to use for loops?:

Comparing do while loop with while loop:

This program compares using a for loop with using a while loop

One Example of Where Using the do while Loop is More Natural Than Using the while Loop:

This program compares uses a do while loop to remove an unnecessary variable initialization

you do not need to initialize the input to be some arbitrary made up value to drop into the while loop
other than initializing input, both blocks of code behaves the same