Logic And Loops

Basic Logic

Boolean

a variable type intended to hold a value of true or false

TRUE

a value of something being valid, often represented with a non-zero number

FALSE

a value of something not being valid, often represented with zero

AND

a logical "and" statement that is true only when both sides are true

OR

logical "or" statement that is true when either side is true

XOR

logical "exclusive or" statement that is true only when one side is true

• This logical operator is very rare and often expressed in bit manipulation which most programmers avoid.
• However this is great trivia in academic tests.
• Read its definition carefully and look at the table in the examples.
• You can also think of it as only true when both values are different.

NOT

logical "not" statement that makes a true into false, false into true, AND into OR, and OR into AND

Truth Table

a diagram used to represent the total possibilities of a logical expression

If's and Switches

if

a block of coding following the if statement is run when the condition is true

else

paired with an if statement, a block of coding is run when condition is false

else if

a chaining technique of else and if statements for selective cases

select/switch

a statement for program flow; it receives a value then runs through the possible case statement under it, if the value equals a case then the lines of code after the case are executed

• A switch statement is very much like a else/if ladder but more eloquently written.

case

one situation for the select statement, if the value given is the same as the case then the following lines are executed

default

these lines of code are executed if no case is matched for the value passed into the switch

Loops

Definite Loop

a loop with a specific number of iterations e.g. for

Indefinite Loop

a loop with an unknown number of iterations e.g. do/while, while

Iteration

one execution of the block of code for a loop

do/while

a loop executed at least once and then when the Boolean value is TRUE

while

a loop executed when Boolean value is TRUE

• This loop is very useful for error checking.

until

sometimes a language will have loops expressed with until; they work just the same but now the loop stops when the Boolean value is TRUE

for

a loop executed during a counting of a variable; the loop is given a starting value, ending value, and amount to increment or de-increment often "i" is the variable

• This loop is very useful for processing arrays.

"Jumping"

break

a statement that breaks flow of program out of one block (i.e. brace couple) of code in a if/else, switch statement

• It is not recommended to use a break statement with a if/else or loop block of code since that block can always be written without the break
• It is recommend to use a break with a switch statement since they cannot be written with the same logic without them.

continue

a statement brings the flow of program back to the condition check in the block

• This also should be treated like a break statement.

Prev -- Back to Portal -- Next